—I saw Kevin in the supermarket this morning.

—No, it ______ him. He moved to Canada last week. [ ]

A. can be

B. must be

C. can't be

D. mustn't be

下列哪项不是建立模型的准则（）

A、适当考虑远景

B、面向问题

C、模型越简单越好

D、制定正确目标