Question

—You can't imagine ________ fantastic fun online chatting is.
—Really？But it may cause a lot of trouble sometimes.

A．what

B．how

C．why

D．so

Answer 1

A

imagine后接了一个由what引导的宾语从句，该宾语从句是一个“what＋adj.＋不可数名词＋主＋谓”结构的感叹句，故A正确。