It was last night ________ I saw the comet.

the time

when

that

which

强调句的结构是：It＋be＋强调部分＋that(who)＋主谓句。强调句的连词只有两个，that和who。当强调的部分是人，且为句子的主语时，才用“who”，其余用that。因此选C。

The most important promises we must keep are          we make to ourselves.

ones

those

these

them

考查代词。句意：我们必须遵守的最重要的承诺就是我们对自己做出的承诺。A. ones泛指上文提到的可数名词复数；B. those特指上文提到的可数名词复数；C. these这些；D.them他们。分析句子可知，为we must 是定语从句，修饰The most important promises，是句子的主语；be动词后缺少表演，we make to ourselves是定语从句，修饰空格处。根据句意，此处指上文提到的promises,由定语从句修饰表示特指，故用 those。故选B项。

You don't have to know the name of the author to find a book. You           find the book by the title.

must

need

can

would

考查情态动词辨析。句意：你不需要知道作者的名字就能找到一本书。你可以按书名找到这本书。A.must必须，一定；B.need 需要；C. can可能；可能；D.would愿意。根据句意可知，此处表示一种客观的可能性，应使用情态动词can。故选C项。

Jenny was very sad over the loss of  the photos she had shot in Canada,          this was a memory she especially treasured.

as

if

when

where

考查连词辨析。句意：珍妮对失去她在加拿大拍摄的照片感到非常悲伤，因为这是她特别珍视的记忆。as 引导原因状语从句，表示“由于”；if“如果”；when“当......什么时候”；where“在哪里”。根据句意，前后文是因果关系，故选A项。

Though ____ the dangers of smoking to their health, smokers still find it hard to give up smoking.

aware of

are aware of

be aware of

考查状语从句的省略：句意：虽然很多经常吸烟的人已经意识到抽烟对他们健康造成了很严重的后果，但是他们仍然发现很难戒烟。Though引导的让步状语从句是省略句，完整的句子是：though smokers are aware of the dangers of smoking to their health。当主从句的主语一致的时候，可以省略从句的主语和be动词，选B

Which of the following does not contain the sound [ae]?

grade

glad

bad

land

考查语音。句意：下面哪个不包含这个发音[ae]? grade的发音是[greId]; glad的发音是[glaed]; bad的发音是[baed]; land的发音是[laend]。故选A项。

So difficult __________ it to work out the problem that I decided to ask Tom for advice.

 I did find 

did I find

 I have found  

have I found

句子使用的基本句式为so…that…结构。按英语语法，当该结构的so…置于句首时，其后的句子(主句)要用倒装语序，如：So loudly did he speak that even people in the next room could hear him. 他讲话声音那么大，隔壁屋里的人都听得见。