原式=a2-b2a+b
=(a+b)(a-b)a+b
=a-b.
He didn't put the things ______ they belonged, for ______ reason he was blamed.[ ]
A. which; that
B. what; this
C. that; whose
D. where; which
换流变压器网侧绕组中性点必须接地运行。