化脓性脑膜炎的MRI表现是()
A.脑表面呈较弥漫的短T信号
B.蛛网膜下腔有不规则强化
C.FLAIR序列显示敏感
D.脑内可出现脑梗死
E.无脑积水征象
参考答案:B, C, D
—______ two little boys behind the trees?
—No, ______. [ ]
A. Is there; there is
B. There isn't; there are
C. Are there; there aren't
D. There aren't; there aren't
离心泵的主要部件包括叶轮、吸入式。