根据明渠恒定非均匀渐变流的基本微分方程，在a区（）。
A.
B.
C.
D.视坡向而定
参考答案：B
—I don't know _______ now.
—She is much better today. [ ]
A. how is she
B. where is she
C. how she is
D. where she is
慢性肾功能不全代谢性酸中毒最好用（）
A.钠型阳离子交换树脂
B.氢氧化铝凝胶
C.叶酸
D.碳酸氢钠
E.血液透析
