d that she (should) stay in bed for a few days.
He demanded that we (should) start right away.
作advice,idea,order,demand,plan,proposal,suggestion,request等名詞的表語從句和同位語從句,其謂語動詞要用虛擬語氣的結構“(should)＋動詞原形”。例如：We all agreed to his suggestion that we(should) go to Beijing for sightseeing.
My idea is that we (should) do exercises first.
在feel, hear, notice, observe, see, watch, have, let, make等詞後的補足語中,不定式不帶to。但是這些句子如果變成被動結構時,就必須帶to。例如：I often hear him sing the song.
He is often heard to sing the song.
注意：不定式動詞在介詞but, except, besides後面時,如果這些介詞之前有行為動詞do的各種形式,那麼,這些介詞後的不定式不帶to,否則要帶to.如：
She could do nothing but cry.
What do you like to do besides swim?
I have no choice but to go.
作定語的不定式如果是不及物動詞,或者不定式所修飾的名詞或代詞是不定式動作的'地點、工具等,不定式後面須有相應的介詞。例如：He is looking for a room to live in.
There is nothing to worry about.
Please give me a knife to cut with.
There / It is no use/ good/ not any use/ good/ useless doing sth.
動詞後可以用動名詞作賓語,但不能用不定式:
admit,appreciate, avoid, consider, delay, enjoy, escape, excuse, feel like, finish, forgive, give up, imagine, include, keep, mention,mind,miss,practise, put off, resist, risk, suggest, can’t help, can’t stand(無法忍受)等。
I tried not to go there.(我設法不去那裡。)
I tried doing it again.(我試著又幹了一次。)]
mean to do 有意... mean doing意味著...
I mean to come early today.(我打算今天早些來。)
Missing the train means waiting for another hour.
(誤了這趟火車意味著再等一個小時。)
allow, advise, forbid, permit
We don’t allow smoking here. We don’t allow students to smoke.
動詞need,require,want作“需要”解,其後跟動詞作它的賓語時,若表示的含義是被動的,必須用動名詞,或不定式的被動式。例如：
The window needs(requires, wants)cleaning(to be cleaned).
在短語devote to, look forward to, pay attention to, stick to, be used to, object to,thank you for, excuse me for 等後的動詞也必須用動名詞形式：I look forward to hearing from you soon.
Badly polluted, the water cannot be drunk.(原因)
Being written in haste, the composition is full of mistakes.
(原因,強調寫的過程,故應用現在分詞一般被動式)
Having been deserted by his guide, he couldn’t find his way through the jungle.(為了強調已完成的動作)
Asked to stay, I couldn’t very well refuse.
這裡 asked 可能意味著 having been asked, 也可能意味著when/since I was asked, 但用了 having been asked 就不會有歧義。
下面句中過去分詞表示的時間與謂語動詞所表示的時間相同，所以不能代之以強調先於謂語動詞的現在分詞完成被動式。例如：
Covered with confusion, I left the room.我很窘地離開了房間。
United, we stand; divided, we fall. 團結則存，分裂則亡。
He used to live in London, use(d)n’t he /didn’t he?
There used to be a cinema here before the war, use(d)n’t there /didn’t there?
Such things ought not to be allowed, ought they?
He ought to be punished, oughtn’t he?
但在正式文體中,用ought we not形式。例如:
We ought to go, ought we not?或We ought to go ,should we not?
含有情態動詞must的句子表示推則,作“想必”解時,疑問部分不可用mustn’t。若前句強調對現在情況的推測,疑問部分用aren’t(isn’t)十主語,例如：You must be tired,aren’t you?若陳述部分的must表示“有必要”時,附加疑問句部分則用needn’t。例如：You must go home right now, needn’t you?
當mustn’t 表示禁止時,附加疑問部分一般用must。如：
You mustn’t walk on grass, must you?
前句謂語動詞是must have＋過去分詞時,若前句強調對過去情況的推測(一般有過去時間狀語),疑問部分的謂語動詞用didn’t＋主語;若前句強調動作的完成,疑問部分的謂語動詞用haven’t(hasn’t)＋主語, 例如：
He must have met her yesterday, didn’t he?
You must have seen the film, haven’t you?
陳述句謂語部分出現否定詞綴時(字首或字尾),疑問部分仍用否定結構。例如:He is unfit for his office, isn’t he?
如果陳述部分包含有no, never, hardly, seldom, few, little,nowhere, nothing等否定或半否定詞時,疑問部分用肯定形式。例如：He is hardly 14 years old,is he?
如果陳述部分的主語為everyone,someone,no one等不定代詞,其疑問部分的主語可用he,也可用they。
Everyone knows his job, doesn’t he?
Everyone knows their job,don’t they?
No one was hurt,were they?
I’m late, aren’t I?
One can’t be too careful,can one(you)?
Have a cup of tea, will you?
Let’s go there,shall we? Let us go there,will you?
同位語從句跟在名詞後面,進一步說明該名詞的具體內容。引導同位語從句的名詞主要有fact, news, promise, idea, truth等。連線詞用that (不用which)及連線副詞how, when, where, why等。例如：
His delay is due to the fact that the car went wrong halfway.
The news that our team has won the match is true.
She asked the reason why there was a delay.
關聯詞只能用whether不能用if表示“是否”的情況如下:
A)在表語從句和同位語從句中。例如：
The question is whether the film is worth seeing.
The news whether our team has won the match is unknown.
B)在主語從句中,只有用it作形式主語時,whether和if都能引導主語從句,否則,也只能用whether。例如：
Whether we shall attend the meeting hasn’t been decided yet.
It hasn’t been decided whether(if)we shall attend the meeting.
C)在介詞之後。(介詞往往可以省略)例如：
It all depends (on) whether they will support us.
D)後面直接跟動詞不定式時。
He doesn’t know whether to stay or not.
E)後面緊接or not 時。
We didn’t know whether or not she was ready.
F)引導讓步狀語從句,只能用whether。
Whether you like it or not, you must do it well.
G)用if會引起歧義時。例如：Please let me know if you like it.
該句有兩個意思：“請告訴我你是否喜歡”。
或“如果你喜歡,請告訴我。”用了whether就可以避免。
在下面幾種情況下必須用“that”引導定語從句：
1)先行詞是不定代詞：all,few,little, much,something,nothing,anything等。All that we have to do is to practise every day.
2)先行詞被序數詞或形容詞最高階所修飾。
The first lesson that I learned will never be forgotten.
3)先行詞被all,any,every, each, few,
