锅炉的()与锅炉房顶部最低结构之间的距离不应小于2m。
A、最高操作点
B、上锅筒
C、上平台
D、安全阀
参考答案:A
I know that it will be difficult to pick him out in such a crowd, but if you ________ happen to see him, give him this packet.
A.would
B.might
C.should
D.could
分化成黄体细胞的有()。
A.卵泡细胞
B.梭形细胞
C.膜细胞
D.成纤维细胞
E.卵母细胞