A:难溶电解质的溶度积越小,溶解度越大
B:可以通过沉淀反应使杂质离子完全沉淀
C:难溶电解质的溶解平衡是一种动态平衡
D:AgCl固体在等浓度的NaCl、CaCl2溶液中的溶解度相同
relaxing, on, hour, useful, an, and, finish, from, favorite, after
Dear Jack,
I am very busy____Friday. At 8:00 I have math. It is not fun. The teacher says it is____ but I think it is difficult.____ that, I have P.E. at 11:00. It is easy____fun. Lunch is____12:00 to 1:00. I have Chinese at 1:20. It is my____subject. My classes____at 2:00, but then I have____art lesson for two____. It is really____.
How about you?
Yours,
Lucy
函数fx=12x2+1x<-2的反函数是( )
给出下列四个命题:
①某班级一共有52名学生,现将该班学生随机编号,用系统抽样的方法抽取一个容量为4的样本,已知7号、33号、46号同学在样本中,那么样本中另一位同学的编号为23;
②一组数据1,2,3,3,4,5的平均数、众数、中位数都相同;
③一组数据a,0,1,2,3,若该组数据的平均值为1,则样本的标准差为2;
④根据具有线性相关关系的两个变量的统计数据所得的回归直线方程为y∧=a+bx中,b=2,x-=1,y-=3,则a=1.其中真命题为( )