蚊子的发育过程经历了: [ ]
A.受精卵→蛹→幼虫→成虫四个时期
B.卵→蛹→成虫三个时期
C.受精卵→幼虫→蛹→成虫四个时期
D.卵→幼虫→成虫三个时期
C
船闸是应用______原理;抽水机是利用______把水从低处抽到高处.
Never before ________ to ________ what his parents expect of him more than it is today. [ ]
A. he has failed; live up to
B. he failed not; come up with
C. has he failed; live up to
D. did he failed; come up with