He was fired his carelessness and laziness.A. because ofB. becauseC. thanks toD. since

问题补充：

He was fired his carelessness and laziness.

A. because of

B. because

C. thanks to

D. since

答案：

(答案→)A. because of

B. because

C. thanks to

D. since

解析：首先根据后边的名词carelessness和laziness排除B、D选项（because和since表原因时用作连词，引导原因状语从句）；because of表原因意为“因为，由于”，thanks to意为“多亏了，幸亏……”，故答案选A。