计算下列各题: (1) ; (2) ; (3) ; (4) . 答案:解:原式= {#mathml#}8b12a2b{#/mathml#} + {#mathml#}9a212a2b{#/mathml#} ﹣ {#mathml#}10a12a2b{#/mathml#}= {#mathml#}8b+9a2−10a12a2b{#/mathml#}
解:原式= {#mathml#}x−yx2−y2{#/mathml#} ﹣ {#mathml#}x+yx2−y2{#/mathml#} + {#mathml#}2xx2−y2{#/mathml#}= {#mathml#}x−y−x+y+2xx2−y2{#/mathml#} = {#mathml#}2(x−y)(x+y)(x−y){#/mathml#} = {#mathml#}2x+y{#/mathml#}
解:原式= It’s
important ______ us to learn from others. It’s wise ______ you to learn from
him.
A. for; for B. of;
of
C. for; of D.
of; for