—Tom hadn’t worked hard and failed in the exam. But he said that was because the problems were too hard.

—That is “    .”

A．a great talker is a great liar.

B．a man can do no more than he can

C．a bad workman always blames his tools

D．It is not work that kills, but worry

对于统计资料的描述可用统计指标和统计图表两种手段。