HS-4001-51是一个（）位置开关。
A.1
B.2
C.3
D.4
参考答案：D
To write your report, you may refer to books _____ 19th century English literature. [ ]
A. from
B. in
C. about
D. at
中国营养学会制定的中国居民膳食营养素参考摄入量中规定，育龄妇女钙的适宜摄人量为（）。
A.800mg/d
B.1000mg/d
C.1200mg/d
D.1500mg/d
E.1800mg/d
