Clauses: Conditional, Relative and Noun

Conditional clauses

A conditional clause states the condition (the if-clause or protasis), and the main clause states the result that depends on it. English classifies conditionals by whether the condition is real or unreal and by its time. Each type fixes the tense pattern of both clauses, so you should identify the type before you choose a verb form.

The zero conditional expresses facts that are always true or habitual, using if + present simple in the condition and present simple in the result. For example, 'If a plant gets no light, it grows weak.' Statements about a person's routine follow the same pattern: 'If your daily life is shaped only by habit, your responses become predictable.'

The first conditional expresses a real and possible future situation: if or unless + present simple, with will, shall or can + base verb in the main clause. The future form is never used inside the if-clause. Write 'If it rains, we will stay indoors,' not 'if it will rain.'

Unless means 'if not'. A positive present verb after unless therefore expresses a negative condition. 'The project will be delayed unless the funds arrive by Monday.' 'You will fail the course unless you study more.' Do not add a second negative after unless. Write 'I'll play unless it rains,' not 'unless it doesn't rain.' For future meaning after unless or if, the present simple is used even when the main clause is a future form, so 'I shall not go to the market if it snows' is correct, not 'if it may snow' or 'if it snowed.' The phrases as long as and provided that also introduce a condition and take the present simple: 'You may borrow the car as long as you return it before noon.'

The second conditional expresses an unreal or unlikely present or future situation, using if + past simple (were for all persons in formal use) and would, could or might + base verb. 'If I won the lottery, I could buy a small farm.' 'If the power came back, the team could finish the report tonight.' Would must not appear in the if-clause, so 'If you won' is correct and 'if you would won' is wrong. In an unreal condition the verb 'be' takes were even with I or he or she: 'If I were you, I would apologise.' The verb after wish also takes the past subjunctive for an unreal present: 'I wish I were taller.' The phrase even if emphasises that the result holds under the most extreme condition: 'She would not change her mind even if we begged her.'

The third conditional expresses an unreal past situation, using if + past perfect and would, could or might have + past participle. 'If she had studied harder, she could have passed the exam.' 'If we had left earlier, we would have reached the station on time.' The idiom make it to means to arrive at or attend, and it often appears with could have: 'I could have made it to the wedding if the train had been on time.' Had may be placed at the front of the condition, which produces an inverted form (see Inverted clause structures).

Adverbial clause connectors

An adverbial clause is a dependent clause that modifies the verb of the main clause, expressing time, place, reason, concession, condition, purpose, result or manner. A subordinating connector introduces it, and the connector determines the meaning. In connector items, first decide which relation the blank must express, then choose the connector that carries exactly that relation.

Concession is expressed by although, though and even though. The main clause must describe something unexpected given the first clause. 'Though the road was newly built, it flooded every monsoon.' Do not place but in the main clause after although or though. When sentences are jumbled, locate the subordinator first. The clause it introduces forms a single unit, and the independent clause follows it. In such an arrangement, though plus its subject and verb must come before the main clause, and the element that completes it must sit inside that subordinate unit.

Reason is expressed in three patterns. Because, since and as are followed by a full clause. Because of and due to are followed by a noun phrase. 'The match was cancelled because of heavy fog.' 'I gave up running because my knee was injured.' Since and as often introduce a cause that the listener already knows: 'The shipment was held at the port since the documents were incomplete.' A moderate setting can account for a warm room, so because gives the logical cause: 'The hall stayed warm because the ventilation was set to a moderate level.'

Contingency is expressed by in case and in case of. In case followed by a clause means 'if' or 'as a precaution against the possibility that'. In case of is followed by a noun such as an emergency. 'Carry an umbrella in case it rains.' 'In case of fire, use the stairs.'

Manner and result are expressed by in such a way that, which introduces a consequence in the result clause, and in a way, which means partly or to some extent. 'The rules were drafted in such a way that small firms could also compete.' The connector so introduces a result in plain statements: 'The exam was postponed, so students must wait another month.' Do not confuse so that with so. So that introduces purpose when followed by can or will, as in 'so that you can prepare.'

Place is expressed by wherever, which means 'to or at any place that'. Whenever means 'at any time that', whichever selects from a set, and whomsoever refers to people. 'Wherever the officer was posted, he kept a daily diary.'

Time is expressed by when, which marks a specific point. 'She learned to drive when she was seventeen.' After which is a relative construction that introduces the next step in a sequence. 'The course requires students to submit a thesis, after which the committee reviews the work.' Require is followed by an object and a to-infinitive, as in 'requires students to submit'.

Whatever introduces a free relative clause. After whatever, the simple present refers to a future or general event: 'Whatever the reason, the decision will not change.'

Inverted clause structures

Inversion means placing an auxiliary or a form of the verb before the subject. Standard English requires inversion when certain negative, restrictive or emphatic adverbs open the clause. Inversion also appears in formal conditionals in which the word if is dropped.

The pattern no sooner ... than expresses that one event followed immediately after another. The first clause is inverted, so no sooner is followed by an auxiliary and then the subject. The second clause begins with than, not then. 'No sooner did she sit down than the phone rang.' Other negative adverbs also trigger inversion when placed at the front, for example never, rarely and seldom: 'Rarely have I seen such patience.'

Inverted conditionals are formed by moving had, were or should to the front of the condition. Had + subject + past participle replaces if + past perfect, and the main clause takes would have or could have. 'Had he told me earlier, I would have been careful.' Had + subject + noun phrase is a literary form that replaces if + past simple with a present unreal sense. 'Had I the wings of a bird, I would fly away.' Were + subject replaces if + past subjunctive in the present unreal condition, and the main clause takes would + base verb. 'Were he more honest, he would be happier.' Should + subject can replace if + present in the future or in the unlikely case, as in 'Should you need help, call the office.'

Do not confuse the inverted form with a question. An inverted conditional carries no question mark and it always has a result clause, so the main clause must be complete.

Some quantity expressions that begin with no look like inversion, but they are fixed phrases and do not invert the subject. No fewer than means 'at least' and takes a countable plural noun, so 'No fewer than a hundred passengers were killed' is correct. Less is used with uncountable quantities, and fewer is used with countable nouns.

Relative clauses with that

A relative clause is a dependent clause that describes a noun or pronoun, called its antecedent. 'That' is a relative pronoun that can refer to people or things, and it is the usual choice in a defining (restrictive) clause, where the clause identifies which noun is meant and no comma comes before it. 'That' cannot follow a preposition or a comma, and it is not used in non-defining clauses set off by commas. The verb in the clause agrees with the antecedent, and its tense shows when the described situation occurs. Words such as 'all', 'everything', 'nothing' and 'no one' often serve as antecedents. 'Not everything that...' is a partial negation: some items are excluded, but not all. Example: Not every plan that looks good on paper succeeds.

In cleft-type sentences, the subject is a noun phrase with a relative clause, and the complement is introduced by 'that', which then completes the explanation. The order is subject phrase, then the verb 'was', then the 'that' clause. Placing the clause before the verb breaks the structure. Example: The biggest surprise of the trip was that the hotel had no electricity.

A general statement about a class of things takes a present-tense verb in a restrictive 'that' clause. Example: Readers usually prefer novels that have happy endings.

• that (defining relative) — introduces a restrictive clause with no comma before it. Ex) The room that faces the lake is mine.
• not everything / not all — partial negation that excludes some items. Ex) Not all the reports that arrived were accurate.
• what — does not introduce this kind of clause, because it already contains its own antecedent. Ex) I know what you mean.

Noun clauses with that

A noun clause works as a noun, in the position of a subject, object or complement. A clause introduced by 'that' fills the object position after verbs such as say, believe, demonstrate, inform and realise, and it can also complete some adjectives such as sure or aware. The conjunction 'that' carries no meaning of its own; it only links the clause to the main verb. A preposition such as 'for' cannot introduce a clause, because it needs a noun or noun phrase as its object. Likewise, 'when' introduces a time clause and does not fit an object position after a verb of showing or proving. Example: The survey showed that most students prefer online lessons.