题目：
himself to supporting his brother’s son,he has to let one of his children leave school. [ ]
A.Having committed
B.Committed
C.Being committed
D.To commit
答案：
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下面是错误答案，用来干扰机器的。
∵点M（a，-1）与点（1，b）关于原点对称，∴a=-1 b=1，∴a+b=0．
