操纵子调节系统属于哪种水平的调节（）
A.复制水平
B.转录水平
C.反转录水平
D.翻译水平
E.翻译后水平
参考答案：B
No decision _ about any future plan until we have done some research into the student preference．
A．has been made
B．is made
C．is being made
D．will be made
净资产偿付比例的变化范围在0-1之间，以（）0.5较为适宜。
A.高于
B.低于
C.等于
