He was fired his carelessness and laziness.
A. because of
B. because
C. thanks to
D. since
网友回答
(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。