鸟卵胚胎发育所需要的营养物质主要来自于[ ]
A.卵黄
B.卵白
C.胚盘
D.气室
答案:A
These comments are not directly ___________ to this enquiry.
A.concerned
B.relevant
C.different
D.involved
CB-CO5A甲烷指示警报器的用途是什么?