生命起源的第二步是由 ___合成蛋白质、核酸等 ___ 。
有机小分子 有机大分子
My English teacher gave us a suggestion yesterday, _____is often the case, ______ our monitor organize a debate after class.
A.which, which
B.which, that
C.as, that
D.as, which
下述“尤文肉瘤”的知识,哪项正确
A.成年人多见
B.常有骨、肺转移
C.常有特征性骨膜反应
D.好发于长骨干骺端
E.髓腔内多有成骨性改变