从生活常识角度考虑，试推断钠元素在自然界中存在的主要形式是 [ ]
A．Na
B．NaCl
C．NaOH
D．Na2O
答案：B
I’ve always dreamt ______ living in a big house. After many years’ hard work, I’m thinking _____ moving and changing my small house ______ a larger one.
A．to; of; into
B．about; about; with
C．of; on; for
D．about; of; for
汽轮机冲转前或停机后，为什么要盘车？
