全变态类昆虫的幼虫在获取足够的营养之后从一个自由活动的虫变态为一个不食不动的过程或现象叫()。
A、孵化
B、蛹化
C、羽化
D、蜕变
参考答案:B
It seems that oil______from this pipe for some time.We’ll have to take the machine apart to put it right.
A.had leaked
B.is leaking
C.leaked
D.has been leaking
下列关于无损检验缩略语不正确的是()
A.RT—射线检验
B.UT—超声波检验实施
C.MT—液体渗透检验
D.VT—目检