the students who took part in the training is 450.
A. A number of
B. A lot of
C. Lots of
D. The number of
网友回答
A. A number of
B. A lot of
C. Lots of
(答案→)D. The number of
解析：考查主谓一致。根据后面的is说明主语是单数形式。而ABC三项是复数形式。D项the number of…指…的数量。做主语时，谓语动词用单数形式。故D正确。句意：参加训练的人的数量是450.