1 . ----Many online games are full of violence, which do harm to the development of the children.
----And that’s _______ my concern lies.

A．what

B．which

C．where

D．that

2 . —I drove to Zhuhai for the air show last week.
—Is that ________ you had a few days off ?

A．where

B．when

C．what

D．why

3 . Is this research center _________ you met some foreign guests last week?

A．that

B．where

C．which

D．in which