硅胶作为液固色谱最常用的固定相，可分为三种，不包括（）硅胶。
A.全多孔型
B.薄壳型
C.非多孔型
D.内部多孔型
参考答案：D
------ Have you seen your nephew lately?
------ Yes, in fact, I saw him yesterday. I ______ him for three years.
A．haven’t
B．didn’t
C．hadn’t
D．don’t
7．—Who would you rather _______ with you for holiday?
—A man _______ himself Wilson.
A．have gone; called
B．have going; calling
C．have go; calling
D．have go to go; calls
