Conjunctions Introducing Conditional Clauses

• You sometimes use modals in conditional clauses to express something desirable, advisable, possible, etc. In the main clause, you can still use a present tense for events that happen often, will for events that are quite likely in the future, would for an event that is unlikely to happen, and would have for events that were possible but did not happen, e.g. If they must have it today, they will have to come at five o’clock. If I could only find time, I’d do it gladly. If you could have seen him, you would have laughed too.

• In simple sentences to express surprise, indignation, disappointment, joy, etc. should + Infinitive is used. Those sentences are emotionally coloured. The modal verb should sometimes weakens its meaning to a great extent, thus approaching its auxiliary function in forming the Suppositional Mood. Should is sometimes used to express greater uncertainty, e.g. If any visitors should come, I’ll say you aren’t here.

• In formal English, if the first verb in a conditional clause is had, should or were, you can put the verb at the beginning of a clause and omit if. For example, instead of saying If he should come, I will tell him you are sick, it is possible to say Should he come, I will tell him you are sick, e.g. Were it all true, it would still not excuse their actions. Had I known, I would not have done it.

• We can use if … not and unless in place of each other when we are saying “except if”. Unless is “stronger” than if not and we sometimes use it in warnings, e.g. Unless you work harder, you are not going to pass the examination. (or If you do not work harder, you are not going to pass the examination.

We cannot use unless in place of if not when if not doesn’t mean “except if”, e.g. I’ll be surprised if he does not win.

We often use unless (never if not) to introduce an afterthought, e.g. I couldn’t have got to the meeting – unless, of course, I had caught an earlier train.

• Besides these conjunctions you can also use as long as, so long as, even if, on (the) condition (that), provided (that), providing (that), suppose (that), supposing (that) assuming (that). These expressions mean “but only if”. E.g. She was prepared to come, provided that she could bring her daughter. Providing they remained at a safe distance, we would be all right.

• In case is not the same as if. Compare these sentences: 1) We’ll buy some more food if Brian comes. (= Perhaps Brian will come; if he comes, we’ll buy some more food; if he doesn’t come, we won’t buy any more food.) 2) We’ll buy some more food in case Brian comes. (= Perhaps Brian will come; we’ll buy some more food now, whether he comes or not; then we’ll already have the food if he comes.) We can also use in case to say why someone did something in the past, e.g. We bought some more food in case Brian came. (= because it was possible that Brian would come)

Note: In case of is different from in case. “In case of fire” means “if there is a fire”, e.g. In case of emergency, telephone this number. (= if there is an emergency)