按皮带机部件性质分类，皮带机的传动部分是（）。
A.电动机
B.减速机
C.滚筒和胶带
参考答案：B
What a table! I’ve never seen such a thing before. It is _____ it is long.
A．half not as wide as
B．wide not as half as
C．not half as wide as
D．as wide as not half
遗传密码的摆动性是指
A．一种氨基酸可以有几种密码子B．密码子的第3个碱基与反密码子的第1个碱基可以不严格配对C．一种密码子可以代表不同的氨基酸D．密码子与反密码子可以任意配对
