假設語氣 (Subjunctive Mood)
假設語氣常見於以 If 開頭的子句 (If-條件句)
If I were you, I wouldn’t keep driving on those tires.
動詞 wish 後面的子句通常使用假設語氣
I wish he were here to learn about it in person.
動詞 act (或 behave, talk, look) + 'as if' (或 'as though')
Susan acts as if she were a queen.
- If I was you, I wouldn't buy that car.
- If I were you, I wouldn't buy that car.
- I wish (that) I was a rich man.
- I wish (that) I were a rich man.
- He talks as if he was the boss.
- He talks as if he were the boss.
She walks as though she _______ drunk.
(A) was (B) were (C) is (D) be
表示提議、要求、命令等概念的動詞（advise, recommend, suggest, propose, insist, request, demand）後面的that子句帶有某些程度的緊迫性，應該用假設語氣的原形動詞。
|that Jerry get more exercises.|
I suggest that he study for the exam.
I recommend that he read the book.
| that she stay overnight.|
I demand that he see me immediately.
The boss requests that everyone be notified of the next meeting.
- I insist that he leaves at once.
- I insist that he leave at once.
虛構主詞 It 帶頭的底下這些形容詞，通常其後 that-子句帶有某些程度的緊迫性，用原形動詞來表示假設語氣。
It is necessary that the problem be solved right away.
It is mandatory that you be there on time.
Is it essential that we (should) be there?