Smoking is one of the of heart disease and it kills lots of people every year.A. causesB.

问题补充：

Smoking is one of the of heart disease and it kills lots of people every year.

A. causes

B. reasons

C. excuses

D. results

答案：

(答案→)A. causes

B. reasons

C. excuses

D. results

解析：词义辨析。A. 引起的原因 B. 理由；理性 C.接口；理由 D. 导致的结果。句意：吸烟是引起心脏病的原因之一，每年致死很多人。结合语境可知选A。