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.
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