When            to someone,I usually say, "Pleased to meet you."

introduce

introduced

introducing

am introduced

考查过去分词和省略。句意：当我被介绍给别人时，我通常会说：“很高兴认识你”。根据句子结构可知，本句是when引导的时间状语从句，原句when I am introduced to someone,这里当从句主语与主句主语一致时，并且从句的谓语动词有be这时从句的主语与be同时省略，所以空格处introduced。故选B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。

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。

With a lot of difficult problems           ,he feels like a cat on  hot bricks.

to settle

being settled

settling

settled

考查非谓语动词。句意： 因为有一大堆难题要解决，他感觉像像热锅上的蚂蚁。本句with +名词+to do sth,动词不定式表示的动作尚未发生或当时看来尚未发生。本句表示“因为有一大堆难题要解决”。故选A项。

The exhibition           next Sunday will feature paintings created by contemporary artists.

hosted

being hosted

to be hosted

hosting

考查非谓语动词。句意：下星期举办的展览将展出当代艺术家的作品。根据句意及分析句子结构可知，此处表示将来发生的事情，应使用不定式作定语，host 与 exhibition 之间是逻辑动宾关系，应使用不定式的被动式。故选C项。