If you ordered through an agent, please check with the agent to ______ that your order was received and processed.

A．insane

B．insult

C．ensue

D．ensure

卫星DNA的多态性是由（）所决定的。

A.DNA点突变个数

B.限制性内切酶识别序列个数不同

C.DNA的二级结构不同

D.重复单位不同

E.重复次数不同