从降压变电站把电力送到配电变压器或将配电变压器的电力送到用电单位的线路都属于()线路。
A、输电
B、架空
C、配电
参考答案:C
I have no________ that he will pass the exam, but I still think there is something about whether
he has really got everything ready.[ ]
A. doubt
B. wonder
C. chance
D. point
自总皂苷元中分离酸性皂苷元,可选用的方法是
A.乙醇沉淀法B.胆甾醇沉淀法C.分段沉淀法D.吉拉尔试剂提取法E.铅盐沉淀法