情態助動詞(modal auxiliaries)

多益 必考文法---英文的助動詞大致上分為兩類：
一種是「沒有語意，只有文法功能」的助動詞，如do, does, did, have, has等。另一種是「具有語意」的助動詞，也就是情態助動詞，此種助動詞多益文法填空題必考(雖然題數並不會太多)，實際上也很常用，非常有必要加以熟 悉，以下我按照各種「語意」做個分類整理。

A. 許可 (permission)
may, can, could (can的過去式), must not …
a. You may leave the office as soon as you have finished. (可以…)
b. You can take three books home with you. (可以…)
c. Last summer break we could stay up late on Sundays. (可以…)
d. You must not leave your car unlocked. (不可以…)

B. 可能、推測 (possibility)
may, might, could, can, must
a. She may/might know Tom’s address. (可能…)
b. He may/might be waiting at the station when we arrive. (可能…)
c. I guess he could be in the library. (可能…)
d. Skiing on the hills can be quite dangerous. (可能…)
e. There is a lot of noise form upstairs. It must be Tom. (一定…)

C. 能力 (ability)
can (=am able to…), could (=was able to…)
a. I can’t (am not able to) pay you today. Can you wait till tomorrow? (沒辦法…)
b. When he was young, he could (was able to) climb any tree in the forest. (可以…)

D. 建議 (advice)
should, ought to, had better
a. You should tell the police about it. (應該…)
b. You ought to phone your parents. (應該…)
c. I think you'd better ask Jane first. (or he will get offended.) (最好…)

E. 必要 (necessity)
must, have to
a. You must use a dictionary. I am tired of correcting your spelling errors. (必須…)
b. We have to wear uniform on duty. (必須…)



參考文獻：
1增進您的英文閱讀、寫作、以及會話技能
2提升學生外語能力之配套措施
3李惠芳 提升學生英語的學與教策略

資料來源：Maxking的英文教室
http://www.jeda.com.tw/Seo_News/News_Detail.asp?News_ID=72&News_Class_ID=0