零时到八九点钟,有许多称谓,如:凌晨、黎明、清晨、早晨等,你知道凌晨是哪一段时间?()
A、零时至六时
B、申时到六时
C、天快亮时
D、天刚亮时
参考答案:A
I like both of these two hats. I can't decide which _____. [ ]
A. take
B. to take
C. taking
D. took
采种静止液体中,各点的()是相等的。
A.位置水头
B.压力水头
C.测压管水头
D.深度