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。

If you don't understand something, you may resrarch, study, and talk to other people          you figure it out.

because

though

until

since

考查连词。句意：如果遇到不懂的东西，你可以搜索、研究，和别人交流直到弄明白。A. 因为； B. 尽管；C.until直到；D.since自从，因为。根据句意可知，until符合语境。故选C项。

We shouldn't take         for granted that we still have a lot of time before the Entrance Examination.

this

that

it

such

考查代词。句意：我们不应该想当然地认为在高考前我们还有很多时间。这里涉及了一个固定句型take it for granted that 认为.....是理所当然的，该句型中it 作形式宾语，真正的宾语是后面that引导的从句。故选C项。

Only then_______ how much damage had been caused.

she realized

she had realized

had she realized

did she realize

“only＋状语”位于句首，整个句子用不完全倒装．此外，由then可确定用过去时态．

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。