可以促进镁吸收的因素有______。
A．氨基酸
B．乳糖
C．葡萄糖
D．水
E．膳食纤维
参考答案：A,B,D
Fractional unemployment is best described as:（）
A. from normal labor turnover.
B. from changes in the skills needed to perform jobs.
C. due to fluctuating unemployment over the business cycle.
透皮给药系统
