He injured his leg and he could not play in the game.A. soB. howeverC. thereforeD. but

问题补充：

He injured his leg and he could not play in the game.

A. so

B. however

C. therefore

D. but

答案：

A. so

B. however

(答案→)C. therefore

D. but

解析：考查副词：句意：他伤了腿，因此不能打比赛了。所以两句话是因果关系，B是副词“然而”意思不符合，A是“因此”但是so是连词，词性不对，D项but是“但是”，也是连词，C是“因此”而且是副词，选C。