非法持有海洛因（）克以上的，构成非法持有毒品罪。
A、5
B、10
C、15
D、20
参考答案：B
—I don't think I'll be able to go mountainclimbing tomorrow.
—________?[ ]
A. And how
B. How come
C. How's it going
D. How about it
当赖兹纳稳定指数（）时，水质稳定。
A、<3.7
B、<6.0
C、≈6.0
D、>7.5
be able to go mountainclimbing tomorrow.