分子式为,分子结构中含有3个“—”原子团的烯烃共有 ( )
A.2种
B.3种
C.4种
D.5种
答案:D
如图所示,有5种同分异构体符合条件:选D。
—Shall we raise some money for the children of Yushu, Qinghai Province?
—_____________. [ ]
A. I see
B. It's a pleasure.
C. I don't believe it
D. That's a good idea.
如果没有特殊参数设定,手动操作3轴数控铣床时,只能移动()个轴的运动。
A.0
B.1
C.2
D.3