请简述水泵比转数（ns）的概念及意义？

湿热腰痛的特点是( )

A．腰部疼痛，重着而热
B．腰痛如刺，痛有定处
C．腰部冷痛重着
D．腰部隐痛
E．腰部酸软无力

血缓冲系统中缓冲能力最强的是 （）

A.NaHCO₃/H₂CO₃

B.Hb

C.血浆蛋白

D.Na₂HPO₄/NaH₂PO₄

E.KHCO₃/H₂CO₃

Tom has to leave now _________ he can catch the train.

A．so that

B．as soon as

C．because

D．if

_____ of the animals is getting _____ because their living areas are becoming farmlands. [ ]

A. A number, large and large

B. A number, larger and larger

C. The number, smaller and smaller

D. The number, small and small

积滞的主要病因是（）

A.外感六淫

B.乳食内伤

C.饮食不洁

D.脾胃素虚

E.肝胃不和