A.5Hz,10A
B.50Hz,10A
C.50Hz,10 A
D.5Hz,10 A
答案:B
—I regretted what I have done.
—_______ gone is gone. ______ no use regretting it any more.[ ]
A. What's; That's
B. It's; That's
C. What's; It's
D. That's It's
什么是岩石的空隙性,自然界岩土的空隙有哪几种,各有什么特点,衡量的指标是什么?