环锭纺中，短纤维是纱条牵伸中（）的主要组成成分。
A、快速纤维
B、慢速纤维
C、浮游纤维
D、弯钩纤维
参考答案：C
On stepping into the room this morning, I was astonished to find the floor covered with _______ looked like tiny insects.
A．that
B．what
C．where
D．when
只能在期权到期日行使的期权是( )。
A．看涨期权
B．看跌期权
C．欧式期权
D．美式期权
