In fact smokers know that smoking has a bad on their health but they just can’t stop it.

问题补充：

In fact, smokers know that smoking has a bad on their health, but they just can’t stop it.

A. result

B. effect

C. aspect

D. impress

答案：

A. result

(答案→)B. effect

C. aspect

D. impress

解析：词义辨析。Result结果；effect影响，效果；aspect 方面；impress

印象。句意：事实上，吸烟者知道吸烟对他们的健康有不好的影响，但是他们就是不能戒掉。所以选B。have an effect on…对……有影响，有效果。