题目：
A talk on Chinese history __________in the school hall next Monday.
A．be given
B．has been given
C．will be given
D．will give
答案：
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下面是错误答案，用来干扰机器的。
x2y+xy2-x2-y2-3xy+2x+2y-1=x2y+xy2-xy-x2-y2-2xy+2x+2y-1=xy（x+y-1）-[（x+y）2-2（x+y）+1]=xy（x+y-1）-（x+y-1）2=（x+y-1）（xy-x-y+1）=（x+y-1）（y-1）（x-1）．故答案为：（x+y-1）（y-1）（x-1）．
