测定哪种元素的有无可区分蛋白质和核酸
A.C
B.H
C.N
D.O
E.S
参考答案:E
___________she was invited to the ball made her very happy.
A.If
B.That
C.When
D.Because
塔机顶升过程中,禁止进行()动作。
A.起升
B.变幅
C.回转
D.起升和回转
E.起升和变幅