实践基础上的理论创新是社会发展和变革的先导。这说明（） A.要通过理论创新推动制度创

He speaks English _______ an American, so we all believe that he has stayed in America for many years. [ ]

A. as good as

B. worse than

C. as badly as

D. as well as

—Why are you looking at me in _____ surprised expression?

─ Don’t you think _____ question you asked is surprising?

A．the; /

B．a; the

C．a; a

D．the; a

热水供应系统中，锅炉或水加热器的出水温度与配水点最低水温的温度差，不得大于（）℃。

A.10

B.8

C.5

D.15

地球内部圈层示意图（下图），回答下列各题。

在地下2900千米处，纵波的传播速度突然下降，横波完全消失，可推测地球内部圈层当中为液体的是（）

A.软流层

B.上地幔

C.下地幔

D.外核