砂按产源分为（）。
A．河砂、黄砂
B．天然砂、黄砂
C．人工砂、河砂
D．天然砂、人工砂
参考答案：D
—How much did you spend on such a nice jacket?
—About 5 dollars.
—What a _____! I thought it would cost 20.
A. price
B. buy
C. bargain
D. cheat
下列软膏基质中，药物吸收最好的是______
A．羊毛脂 B．凡士林C．乳剂基质 D．蜂蜡E．聚乙二醇
