问题
Is that the reason ______ at the meeting for his carelessness in his work? Actually we think he is a man whois hard ______ himself especially in work[ ]
A: that he explained to all; on
B: what he explained all; with
C: why he explained to all; at
D: which he explained to all; to
B: what he explained all; with
C: why he explained to all; at
D: which he explained to all; to
正确答案是：
