—Did you know China is one of the oldest countries in the world?
—Yes, I did. It’s ______ than the US.
Which do you prefer to use to keep in touch with your friends, QQ_____ WeChat?
如图,空间四边形ABCD的对角线AC,BD相等,顺次连接各边中点E,F,G,H,则四边形EFGH一定是( )