主语从句在复合句中做句子的主语。引导主语从句的词有连词that, whether; 连接代词 who, what, which; 连接副词 when, where, how, why等。接下来给大家罗列几个经典的主语从句例句。
如：
What is needed for the space trip is careful preparation.
Whether wild life can be well protected is of great importance.
Who will go makes no differences.
Why dinosaurs died out remains a puzzle.
Which kind of food is the best is still not certain.
为了避免主语显得过长，可以用it 作为句子的主语，把主语从句移到句子的末尾。如：
It hasn't been decided yet when the new restaurant will open.
It is not clear how gold was found there.
It is hard to understand why there is gravity.
It is a shame that you have to leave so soon.
