---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。

Like other animals, we are          until we know it is safe to relax.

on purpose

on fire

on guard

on duty

考查介词短语辨析。句意：像其他动物一样，我们在知道安全的时候才放松警惕。A.on purpose 故意；B. on fire着火；C.on guard 警惕；D.on duty值班。结合后文we know it is safe to relax，可知我们在知道安全的时候才放松警惕。故选C项。

Great amounts of water            poured into the river from the factories two years ago.

was

were

has been

have been

考查时态和主谓一致。句意：两年前，工厂将大量废水排入河中。根据two years ago 可知，句子使用一般过去时。....amounts of修饰不可数名词作主语时，谓语动词用复数形式，即谓语动词与amounts保持数的一致。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。

Writing out all the invitations by hand was more time-consuing than we             .

will except

are  excepting

except

had excepted

考查时态。句意：手工写下所有的邀请函要比我们预料的花去更多的时间。根据句意可知我们预料是在实际上写之前发生的，而本句中实际写花去的时间使用了过去时was，所以expect用过去完成时。故D项正确。

---It's burning hot today,isn't it?

---Yes,_____yesterday.

So was it

So it was

So it is

So is it

句意：“今天太热了，是不是？”“是呀，昨天也一样”。如果表示前面所说的肯定情况也适合于另一者，要用“so+助动词/情态动词/系动词+主语”。