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。

When it comes to modern communication, network safety is always a major          . 

concern

advantage

opportunity

solution

考查名词辨析。句意：当涉及现代通信，网络安全一直是一个主要令人担忧的问题。A. concern关心，令人担忧的事实或情况；B. advantage 优势；C. opportunity 机会；D.solution解决方案。网络安全一直是现代通信的个主要令人担忧的问题。故选A项。

Why don't you             ? Try to make it a win-win situation for you both.

compromise

object

salute

rate

考查动词词义辨析。句意：你为什么妥协呢？试着为你们双方创造

双赢的局面。A.compromise妥协；B.object反对；C.salute致敬；D.rate比率。由后文试着为你们双方创造双赢的局面，可知前面讲的是妥协。故选A项。

I would really appreciate       if you can make time in your schedules to attend my lecture today.

that

it

this

one

考查形式宾语。句意：如果你今天能从日程安排中抽出时间来听我的讲座的话，我将不胜感激。I would appreciate it if/when...如果/当...时，我将非常感激。it 做形式宾语。故选B项。

it was at 10 pm yesterday______he came home from work.

that

when

which

what

考查强调句。句意：昨天晚上10点他下班回家。考查it+be+强调部分+that+句子，选A。

—Have you watered the flowers?

I am

I’m going

I’m just going to

I will go

句意为：——你浇花了吗？——没有，不过我正打算浇。I’m just going to.相当于I’m just going to water the flowers。故选C。

There                   in the world              China is a great country with a long history and rich culture.

are no doubt; that 

are not doubts; if

is no doubt; that

is not doubt; if

考查固定句型和同位语从句。句意：毫无疑问，中国是世界上有着悠久历史，丰富文化的一个大国。分析句子可知，这个句型为 there is no doubt that 引导，表示“毫无疑问......”.本句为that that 引导的同位语从句，句意和句子结构完整。故选C项。