— It's eight o'clock already. Jack _____ be here by now.

— Oh, he told me that he was going to see his dentist and wouldn't be back until ten. [ ]

A. must

B. can

C. should

D. need

国际组织采购咨询服务时广泛采用的咨询机构选择方式是（）。

A.公开招标

B.邀请招标

C.竞争性谈判

D.两阶段招标