—I don’t really like Janes. Why did you invite him?

—Don’t worry. He       come. He said he was’t certain what his plans were.

A．must not

B．need not

C．would not

D．might not

PUC质粒作为基因克隆载体应有下列何种调控元件（）

A.AmPr

B.ori复制子

C.LacZ标记

D.多克隆位点