在克隆动物的过程中,移植的细胞核一般不能来源于 [ ]
A.乳腺细胞
B.卵细胞
C.胃腺细胞
D.囊胚时期的胚胎细胞
答案:B
(2013·高考新课标全国卷Ⅱ)When I arrived,Bryan took me to see the house________I would be staying.
A.what
B.when
C.where
D.which
若进出口压差超过1bar,则说明预过滤器滤芯应更换()