1what引导的主语从句中
主句谓语用单数
但是从句中的谓语（what作主语）用但数还是复数
还是看指代？
接触的主从不多，还有什么疑问词引导（初中，很多不知道，写作文想叠一叠）
2倒装句除了only引导还有什么高级的表达

What引导主从并且what在从句中也作主语的话，从句内部用单数。
What really matters is that you should put your ideas into practice.
What is known to us all is that paper was first made in China.
What引导主从并且what在从句中不做主语的话，就具体按人称代词变化
What she needs is more practice.
What I want to know is this.

勿喷