4x2y3÷(-12xy)2
=[4÷(-12)](x2÷x2)(y3÷y2)
=-8y.
故答案为-8y.
I want my mother ____________ a pencil case for me. [ ]
A. buy
B. buying
C. to buy
成人细菌性脑膜炎的常见临床表现和体征不包括()
A.发热
B.头痛
C.意识障碍
D.癫痫样发作
E.颈强直