利用重力沉降原理所能分离除去的最小液滴为（）μm。
A.100
B.120
C.150
D.200
参考答案：A
—— You ought to have given them some advice
---- _____, but who cared what I asked?
A．So ought you
B．So 1 ought
C．So it was
D．So I did
树种选择的基本原则是（）。
A、满足造林目的和满足树种生物学特性
B、满足树种生物学特性和立地条件特点
C、满足造林目的和达到适地适树
D、达到适地适树和立地条件特点
