【题目】The tech industry expo, which attracted more than 180, 000 people, was a reminder of the tech industry is best at: being optimistic about itself.
A. thatB. how
C. whatD. which
在线课程【答案】C
【解析】
考查介词的宾语从句。句意：吸引了18万多人参加的科技产业博览会提醒人们，科技产业最擅长的是:对自己保持乐观。此处介词of后面是一个宾语从句，从句没有引导词，且从句谓语部分缺少主语，所以用what其双重作用，故选C。