4.When the teacher entered into the classroom,we____at once.
A.were stopping talking B.were stopping to talk C.stopped talking D.stopped to takl

16.My dog has _____for more than a week.
A.gone away B.stayed away C.put away D.taken away

18.Jane and Xiaoling____their homework the whole night.
A.was doing B.have done C.were doing D.are doing

9.The work was ____difficult ____I couldn't finish it.
A.too;to B.so;that C.such;that D.too,that

10.We find him little ____.We don't like him.
A.politely B.polite C.impolitely D.impolite

20.This teapot is filled ____ tea.
A.with B.of C.in D.for

都是单选题，答案是什么，为什么其它不行

4.When the teacher entered into the classroom,we____at once.
A.were stopping talking B.were stopping to talk C.stopped talking D.stopped to talk
搭配:stop to do sth 翻译为:停下来去做另一件事
stop doing sth翻译为:停止做未完成的事
句子翻译为:当老是进入教师时,我们立刻停止讲话.
这里用一般过去时即可.AB可排除.
D项翻译为:停下来讲话,很明显与句意违背.
综上:选C


16.My dog has _____for more than a week.
A.gone away B.stayed away C.put away D.taken away
A gone away 走开;离开
Bstayed away 外出
Cput away 放好
Dtaken away 带走
句子翻译为:我的狗已经丢失了超过一个星期了.
gone 表示去了某地还未回来.
选A

18.Jane and Xiaoling____their homework the whole night.
A.was doing B.have done C.were doing D.are doing
the whole night提示了 动作发生持续了整夜,应该用进行时态.
Jane and Xiaoling是指两个人,Be动词要用复数形式,可排除A
B现在完成时态,强调过去的事情对现在的影响或造成的结果.不符合句意,可排除.动作发生在过去,因为the whole night已经过去了.可排除D
综上:选C

9.The work was ____difficult ____I couldn't finish it.
A.too;to B.so;that C.such;that D.too,that
too...to..=so ...that =such ...that.翻译为:太....而不能...
结构:too+形容词+to+动词原型
so +形容词+that+句子
such +形容词+名词/代词+that+句子
综上:选B

10.We find him little ____.We don't like him.
A.politely B.polite C.impolitely D.impolite
little 翻译为:几乎不;稍微;很少;在这里作为副词用.修饰形容词.本身有否定的意思.
句子翻译为:我们发现他一点也不礼貌.我们都不喜欢他.
Dimpolite 不礼貌的 如果选D上去,就变成双重否定,就变成了礼貌的意思.AC是副词,可排除.
综上:选B
20.This teapot is filled ____ tea.
A.with B.of C.in D.for
固定搭配:be filled with=be full of 充满...
综上:选A