下列可引起脉压缩小的是（）
A.动脉导管未闭
B.主动脉瓣狭窄
C.甲状腺功能减退
D.高热
E.老年人动脉硬化
参考答案：B
Those T-shirts are usually $35 each, but today they have a ______ price of $ 19 in the Shopping Centre.
A．regular
B．cheap
C．special
D．different
薄层色谱法的英文缩写是
A．EC
B．GC
C．HPLC
D．TLC
E．PC
