什么是表语从句

表语从句指的是用来做主语、宾语、或补充说明主语、宾语的被链接动词连接的句子。它通常用于答句中，对主句的主语或宾语进行补充、说明或描述。表语从句通常由连词（如that, whether, who, whom, whose, which, what, when, where, how等）引导。例如：
- My dream is that I can travel around the world.（that从句作is的表语）
- The question is whether she will come to the meeting.（whether从句作is的表语）
- He is the person who won the first prize.（who从句作is的表语）
- The problem is what we should do next.（what从句作is的表语）