【单选题】如图 1 是某校 50 名学生素养测试成绩的频数分布直方图 . 下列式子中, 能较合理表示这 50 名学生的平均成绩的是( )
A.
25+15+10 ( 25×70+15×80+10×90 )
B.
25+15+10 ( 25×80+15×90+10×100
C.
25+15+10 ( 25×75+15×85+10×95
D.
25+15+10 ( 25×76+15×83+10×99
【简答题】______参数是指某项参数直接表示了系统某个参数的真实值。
【判断题】N型半导体是在本征半导体内掺入微量的三价元素杂质。
【单选题】With exports _______ an important role in its economic growth now, this province has been affecte
A.
35.With exports _______ an important role in its economic growth now, this province has been affected by the global economic downturn. A.played
【简答题】形式参数是指在( )时使用的参数;实际参数是指在( )时使用的参数。
【单选题】The study of Dr. Ruth Mace and Dr. Rebecca Sear shows that a child's growth may be affected ______.
A.
by the absence of the mother
B.
by the negligence of the father
C.
by the death of the grandmother
D.
by the death of the grandfather