因式分解：
4a（b-a）-b2。
解：原式=4ab-4a2-b2
=-（4a2-4ab+b2）
=-（2a-b）2。
He eats __________ food, so he is __________ fat.[ ]
A. much too; too much
B. too much; much too
C. much too; the many
D. too much; too many
采煤机工作时，电动机输出的功率主要消耗在（）上。
A、装煤
B、调高
C、牵引
D、截煤
