有說一個簡單英文句子只有一個動詞,但確切點說,是只有一個「主要動詞」(main verb)。Main verbs用以表達句子主語(subject)的動作。除了main verbs之外,還有兩類動詞—auxiliary verbs(助動詞)和modal verbs(情態助動詞),作用都是賦予main verbs特定的意義。這次主要談談modal verbs。
Modal verbs表達說話者的想法或態度,包括:
1 ) 表示推測:must、may、might、can、could
上述modal verbs表達推測的語氣。Must表示非常肯定,例如:Sam is absent. He never skips classes for no reasons. He must be sick today.
如果沒有那麼肯定,只是「可能」,可以用may、might、can或could。譬如說:I'm not so sure. He could be sick, or he could be out of town.
幾乎肯定沒有可能,就應該用can't。如:It can't be true!
2 ) 表示請求:may、might、can、could、will、would
請求問句中,如果主語是I,可用may、might、can或could開頭。例如:May I borrow you book, please?
Might I最為客氣,但現已比較少用;May I和Could I較常見,都是禮貌的表達方式;Can I就最不客氣,只用於相熟朋友之間的對話。
如果主語是you,則可用can、could、will或would。例如:Would you pass the salt?
Could you和Would you的語氣比Can you和Will you禮貌和客氣。
3 ) 表示必要:must
例子:All students must pass the examination in order to graduate.
4 ) 表示建議:should、ought to、had better、could
Should和ought to的意思差不多,都是「應該」,如:You should study harder.
Had better的語氣較重,暗示不依建議做的話會有不良後果,如:We'd better hurry up or else we may miss the flight.
Could的語氣最弱,通常表示一個選擇,如:You could take a bus to the airport, or you could take a taxi.
從以上例子可見,would、could、might不一定是will、can、may的過去式。此外,在第一和第四類情況,若講述過去的事情,應該用must have、might have、may have、could have、should have。例如:
•推測過去發生了甚麼事情:Sam was absent yesterday. He might have been sick. (不是He might be sick.)
•指出原本應該怎樣做:I have a cold. I should have worn a coat last night. (Ought to have和had better have並不常用。)
上述部分modal verbs還有另一些意思,例如can和could可表示能力,may和might表示許可等。要掌握不同modal verbs的用法和差異,可以多參考文法教材。 ■葉劉淑儀 新民黨主席
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