5xy2-{2x2y-[3xy2-(xy2-2x2y)]÷(-12xy)}_爱下问搜题

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问题解答题

5xy2-{2x2y-[3xy2-(xy2-2x2y)]÷(-

1

2

xy)}

答案

原式=5xy²-{2x²y-[3xy²-xy²+2x²y]÷（-

1

2

xy）}

=5xy²-{2x²y+4y+4x}

=5xy²-2x²y-4y-4x．

选择题

The research mainly deals with the difficulty the students have ________ their attention on their study all

the time.[ ]

A．to focus

B．to be focused

C．focusing

D．focused

填空题

2A11灰斗发出高料位报警，应停运（）号高压柜。