As crossing

While you cross

While crossing

Cross

这题考查时间状语从句的省略式，当主从句的主语一样时，可以省略从句的主语和be动词，这题的while crossing就省略了you are，句意是：当你过马路时，别忘了两边看看。选C。

We’ll make the final decision on our scheme. ______ you change your mind, please inform us as soon as possible.

Should

Were

Would

Had

考查虚拟语气的省略。句意：我们将对我们的计划做最后决定。如果你改变主意，请尽快通知我们。根据语境，此处用虚拟语气，表示与将来相反，从句用should+动词原形，省略if，should提前，陈述句是：If you should change your mind……。故选A。

---What is your first impression          our English teacher?

---He is patient but he is strict         us.

with; in 

to; with

of; with

of; at

考查固定短语。句意：---你对我们英语老师的第一印象是什么？---他很有耐心，但对我们很严厉。两句话中介词的宾语都是人，第一句要用impression of sb表示“对某人的印象”；第二句中则要“be strict with”表示对（某人）严格。故选C项。

 Is _______ three hours _______ the poor boy to come to school on foot?

it; that it takes

there; that it takes

there; when

it; that

考查强调句。强调句的结构为It’s + 强调部分 + that从句。本题强调时间状语three hours。句意：可怜的男孩步行到学校花了3个小时吗？故A正确。

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。

Don't forget            the letter for me when you pass  by the post office.

post

to post

posted

posting

考查不定式作宾语。句意：你经过邮局时别忘了替我寄这封信。forget to do sth忘记要做某事；forget doing sth 忘记做过某事。根据句意表示事情已经发生。故选B项。