将主动或从动链轮之一侵入油池中连续润滑的是（）
A.人工定期润滑
B.滴油润滑
C.油池润滑
D.压力润滑
参考答案：C
设有char *a="ABCD"，则printf("%c"，*a)的输出是______。
— _____ did Prince William's wedding (婚礼) last?
— It lasted for about 5 hours.
A. How far
B. How long
C. How soon
D. How often
