A study shows the students who are engaged in after-school  activities are happier than        who are not.

ones

those

these

them

考查代词。句意：一项研究表明，参加课外活动的学生比不参加课外活动的学生更开心。空格处代词与the students是对应关系，可以用the ones 或者those替代。“them”指代前面提到的复数名词，不能与the students形成对应关系，“these”一般不用定语从句修饰。故选B项。

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。

My mom suggest that we           eat out for a change this weekend.

should

might

could

would

考查虚拟语气。句意：我妈妈建议我们这周末出去吃饭换换口味。suggest作“建议”时，后面的宾语从句要用虚拟语气（should）+动词原形。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 has been warned that        to the surroundings with people infected by Covid-19 without any

protection can lead to severe result.

being exposed

exposed

having exposed

to expose

考查非谓语动词。句意：有人警告称，在没有任何保护措施的情况下，暴露在有感染 Covid-19的人环境中会导致严重的结果。分析句子结构可知expose在句中应用非谓语动词形式，表示“暴露”短语为be exposed to,且从句中缺少主语，expose 与主语people是被动关系，故应用动名词的被动式作主语。故选A项。

Really? You        twice the price to buy the book!

paid

took

spent

cost

考查动词词义辨析。句意：真的吗？你付了2倍的价格买这本书！四个动词都有“花费”的意思，但用法不同。pay的主语通常是人，常用结构是 sb pay (money) for sth;take作“花费”时讲常用于固定句型 It takes/took sb (money/time)to do sth做某事花费某人（金钱/时间）；spend的主语通常是人 sb spend...on sth 或sb spend ...(in) doing sth;cost的主语通常是物，sth cost sb (money)意为“某物花了某人多少钱。本题主语是人，结合句意和后文to buy the book，空格处应填pay。故选A项。

Perhaps they have experienced something similar and do not want you to           the same pain.

go over

go through

go around

go on

考查动词短语辨析。句意：也许他们有过类似的经历，不希望你经历同样的痛苦。A. go over复习，重温；B. go through经受，通过；C. go around 四处走动，流传；D. go on继续。根据the same pain可知，此处是“经历，经受”的意思。故选B项。

I_____you can finish the exam in two hours.

does believe

do believe

did believed

do believed

句意：---我确实相信两个小时内能完成考试。这里用来强调，在谓语动词前加助动词do表示强调。句子的主语是第一人称，所以位于动词不能用单数，故排除A；did后用动词原形；do后用动词原形，故选B。

Only when he returned ________ that the war had ended and the army had come back.

we tell

we told

did we tell

were we told

考查倒装句型。Only放在句首时，句子要用倒装语序；根据句意“我们被告知”可知，此处要用were we told。故答案选D。

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。