worries me the way he keeps changing his mind.
A. This
B. That
C. What
D. It
网友回答
A. This
B. That
C. What
(答案→)D. It
解析：it作形式主语,真正的主语是the way he keeps changing his mind。因为主语太长,而用it作形式主语。that用于指眼前的、说过的事物或人,又指比 this 稍微远一点的东西,意为“那，那个东西，那件事情”。what用于引导名词性从句；this意为“这,这个,这事”。