John couldn’t take part in the activity held at the cultural center yesterday for reasons.
A. series of
B. all kinds
C. the number of
D. a variety of
网友回答
A. series of
B. all kinds
C. the number of
(答案→)D. a variety of
解析：考查词组：句意：约翰因为各种各样的原因不能参加昨天文化中心举行的活动。a variety of
各种各样的，A应该是a series of，B应该是all kinds of，C是…的数量，选D。