Definition of Auxiliary Verbs:the word help the main verb making a tense

兼用助動詞︰ am, is, are, was, were, have, has, had, do, does, did, need, dare, used專 用 助 動 詞 （ 亦 稱 “ 情 態 助 動詞 ” ） ︰ shall, should, will, would, can, could, may, might, must, ought, had better

1. 兼用助動詞︰既可當助動詞又可當主動詞的動詞

• am, is, are, was, were, have, has, had, do, does, did, need, dare, used

助動詞 主動詞Lisa is reading a novel. Lisa is a student.

He does not live in . He does his homework carefully.

You needn’t tell her the truth.

You need a new dress.

We used to sing songs in KTV.

We used a pen to write.

2. 專用助動詞︰只可作助動詞不可當主動詞的動詞

shall, should, will, would, can, could, may, might, must, ought, had better

• You should study hard.

• He can run very fast.

• Mary may not come tomorrow.

3. 助動詞的特點︰

(1) “ 專用助動詞”無人稱與數的變化• I (He, Lisa, We, They) must study hard.

• You can run fast, and he can too.

(2) “ 專用助動詞” 中僅 ought 後接 to V ，其 餘皆直接加動詞原形• You ought to be very careful.

• He will buy a gift for you.

(3)“ 兼用助動詞”之後有的有 to ，有的則無• I don’t know him.

• I have to leave for Taipei now.

(4) need （必需 / 需要） / dare （敢）在否定句及疑問句中要加省略 to 的不定詞

• I daren’t go out alone at night.

• Need I get up at five a.m. tomorrow?

(5) 過去式的助動詞未必指過去的事，可能是指現在或未來，除非上下文有明顯的過去時間或談到過去的事

• Could you lend me a pen?

《註》請問或拜託時，用 could 比較正式； 也可用 can ，但多用於熟人的情況， would 情況亦類似

• You should take care of your dog carefully.

《註 》 should 除作 shall 的過去式外，在表示主詞的責任或義務“應該” 時要用should 而非 shall