​was/were able to 用來描述過去特定的情況

e.g 店七點就關了，但我們那天可以多逛15分鐘

我打了五通電話，總算打進去專線。

​must 表示 義務/必要的行為動作→無過去式/請改成had to

e.g. 發燒了/一定要看醫生

下次有屏東的時候/一定要聚一下

能力

必要

​ability 能力 necessity 必要

​must 不用被動

請改had to

​was/were able to

用來描述過去

特定的情況

可能性

允許

• "Can I borrow your pen?"

• "It can rain later today."

• "May I go to the restroom?"

• "He might be late for the meeting."

• Could I use your phone, please?"

• "She could win the competition."

• "They may come to the party."

• "I must study for the exam."

• "They're not here. They must have gone home."

• You can't take food on the subway.

• You might get your test paper today.

1

2

3

4

5

6

7

8

9

10

11

• "Can I borrow your pen?"

• "It can rain later today."

• "May I go to the restroom?"

• "He might be late for the meeting."

• Could I use your phone, please?"

• "She could win the competition."

• "They may come to the party."

• "I must study for the exam."

• "They're not here. They must have gone home."

• You can't take food on the subway.

• You might get your test paper today.

1

2

3

4

5

6

7

8

9

10

11

• "Can I borrow your pen?"

• "It can rain later today."

• "May I go to the restroom?"

• "He might be late for the meeting."

• Could I use your phone, please?"

• "She could win the competition."

• "They may come to the party."

• "I must study for the exam."

• "They're not here. They must have gone home."

• You can't take food on the subway.

• You might get your test paper today.

permission

possibility

permission

possibility

permission

possibility

possibility

possibility

possibility

permission

possibility

We use different auxiliary verbs(助動詞) to

show possibility and permission.

can/could/may/might/must

5

4

Categorize the auxiliary verbs into 2 groups.

There are 5 for the former and 4 for the latter.

can/could/may/might/must

5

4

can/could/may/might

can ___________.

you

work out

at the gym

may _________.

Jay

stay home

today

might _________.

Susan

come to

the party

after class

must _________.

Milk

be kept

in the refrigerator

could _________.

Milk

be kept

in the refrigerator

可能的程度

從低到高

must not 在美式英文的意思常表示

"某件事不可能/不是真的，但can't/cannot較常用

過去可能發生的事情

詢問允許的禮貌程度

could have +Vp.p 用來表達過去未被實現的事件/機會

may 不常用過去式