6.1        Conditional Sentences

Day 1  Zero Conditional and First Conditional

Conditional sentences consist of two clauses, a conditional clause (or if-clause1) and a main clause. The event described in the main clause depends on the condition2 described in the if-clause.

條件句是由兩個從句所組成的，一個是條件句 (if-clause)，另一個是主句，在主句中的事件會由條件句中的條件所影響。

Order of the clauses 從句的次序

It is very common to place the if-clause at the beginning and connect the two clauses with a comma :

把條件句放在開頭，然後用一個逗號把兩個從句連起來是一個很常見的條件句排列法 :

You can also place the if-clause after the main clause. However, there is no need for a comma in this case:

你亦可以把條件句放在主句之後。但是，在這情況不需要使用逗號 :

1 :   Since the most common conditional conjunction is if, we also call the conditional clause shown in the example the ‘if-

       clause’.

2 :   A CONDITION is something which may or may not happen, depending on circumstances.

       條件是指一樣事情會根據環境，會或者不會發生。

Note: We can place then in front of the main clause to emphasize the preceding if. 我們可以在主句中加上 ’then’ 來強調和加重語氣。

e.g. If you press the button, then the door opens.

Types of Conditional Sentences

There are four main types of condition expressed by the if-clause:

在英語中，一共有四大類條件句的模式 : Type 0, 1, 2, and 3.

(A) Zero conditional

(B) First conditional

(C) Second conditional

(D) Third conditional

Let’s start with zero conditional!

(A) Zero conditional

Zero conditional is also called ‘generic factual conditional’. It expresses relationships that are true and unchanging.

Type0的條件句被稱為事實條件句。用於描述是真的，不變的事實。

Basic form:

Note: It is used for talking about general truths, scientific facts and sometimes general habits. This has the simple present in both clauses, meaning that the condition here can be true at any time.

這個形式是用於一般的事實，科學的事實，以及一些普遍的習慣。

這個形式的主句和條件句都是現在式，意思是這個條件在任何情況下都是真，都成立的。

E.g.

In this type of condition, if means almost the same as WHEN or WHENEVER.

在這個形式的條件式下，‘ if ’ 的意思是跟 ‘WHEN’ 或 ‘WHENEVER’ 一樣的。

(B) First conditional  

First conditional is also called ‘future (or predictive) conditional’. It expresses future plans or contingencies.

Type1的條件句被稱為未來/預言性的條件句。它表達未來的計劃或意外事故或偶然事件。

Basic form:

Note: The main clause in first conditional is the ‘likely result’ that is predicted to happen, if the condition is true. It is commonly used for talking about possibilities in the present or in the future. 這個形式的主語從句中所表達的是若條件句成立，便被推算為很有可能發生的結果。 這個形式常用於談及在現在或將來的可能性。

E.g.

Note: In this type of conditional, when (or whenever) cannot be used to replace if, because when is used for events which will definitely happen.

在這種形式中， ‘when 或 whenever’ 不可能代替 ‘ if ’。

However, sometimes the future outcome expressed in the ‘main clause/result clause’ is not that certain. In that case, we may use may or should for the weaker prediction.

但是，有時主句中所表示將來的結果是不肯定的。在那種情況下，我們可以使用 ‘may’ 或 ‘should’ 來表示較弱的估計。

E.g.

Thus, the prediction scale for using different modal verbs also applies to the result clauses of first conditional sentences:

由此可見，選用不同的情態助動詞可以表示出不同程度的結果。

Note: The level of certainty decreases from will to might.

Let’s do some exercises now!