在薄层定性鉴别中，最常用的吸附剂是（）
A.硅胶G
B.微晶纤维素
C.硅藻土
D.氧化铝
E.聚酰胺
参考答案：A
Before attending the NPC held in Beijing as a deputy ,he had made a lot of investigations about
this issue, _____ turned out to be a wise decision. [ ]
A. that
B. which
C. when
D. where
“西气东输”工程不经过的区域是 [ ]
A、西北地区
B、北方地区
C、南方地区
D、青藏地区
