从同一胚叶的一种分化成熟细胞或组织转变为另一种成熟细胞或组织的过程称为
A．间变
B．化生
C．增生
D．再生
E．瘤性增生
参考答案：B
-- - Alison, I’m sorry. I can’t come to the wedding with you tomorrow morning.
-- ________?
-- My grandma was severely ill, so I have to stay in the hospital to look after her.
A．How is it
B．How come
C．So what
D．What’s the problem
轨道提升斜巷必须装备拖绳轮，气间距不得大于（）米。
A.20
B.30
C.40
-- ________?