丈量一段距离6次，结果分别为365.030m，365.026m，365.028m，3

某投资者将一部分闲余资金投资于证券市场，希望能够获得非常高的回报率，那么，他应该选择的投资对象是( )。

A．公司债券

B．指数基金

C．高科技股票

D．蓝筹股

短文改错

     Recently, my classmates have had a heated discussion about if we should have optional courses

(选修课) in high schools. Some students were  in favor of optional courses. They say interest is best

teacher and  our spare time will be colorful and meaningful. Students can not only  enlarge their

knowledges but also improve their abilities.  However, others are against the idea, said that optional

courses will take up too much time as well as energy. Besides, some optional courses have something

to do with the College Entrance Examination. They are afraid they'll fall behind their classmates if they

will take optional courses. I'd like to take one or two  of the optional courses, which, I think, will certain

benefit me  lot.

_____________________________________________________________________________

影响社会政策执行效果的因素主要有哪些？

下列属于本轮规划调整的品种的是（）

A、南方早熟梨和榨菜

B、水稻、马铃薯、“双低”油菜、柑橘、蚕桑

C、茶叶、优质瘦肉型猪、山羊、名优水产品

D、玉米、小麦、蔬菜、肉牛和家禽

影响膜截留率的因素有哪些？