of the students who took part in the military training is 450.A. A numberB. A lotC. LotsD

问题补充：

of the students who took part in the military training is 450.

A. A number

B. A lot

C. Lots

D. The number

答案：

A. A number

B. A lot

C. Lots

(答案→)D. The number

解析：考查数词。根据句中的谓语动词用单数，可知用the number of……的数目，其它选项谓语动词用复数。选D。