由what等代词引导的主语从句: what表示“…所…的(东西)”, 在结构上等于一个名词加一个定语从句; whatever表示“所…的一切”; whoever表示“一切…的人”.
What you need is more practice
What is hard is to do good all one’s life and never do anything bad.
Whatever was said here must be kept secret.
Whatever I have is at your service.
Whoever comes will be welcome.
Whoever fails to see this will make a big blunder.
