What引导的主语从句中，从句的谓语动词是什么形式？用单数还是复数？
譬如下面两句，应用哪句？
What counts is your comments.
What count is your comments.
习惯上是用单数。如：
What is done cannot be undone. 已做的事是既成事实。
What lies at the root of his troubles is a sense of insecurity. 他的所有忧虑来自于一种不安全感。
What matters for most scientists is money and facilities. 对大部分科学家来讲，要紧的是经费和设施。
What makes it difficult for the communities to coexist peacefully? 是什么使得群体之间很难和平相处？
What worries some of us is that the Prime Minister may feel simply unable to do a somersault. 使大家中间的一些人担忧的是，首相或许感觉根本就没办法做到180度的态度大转变。
