解不等式:(ax-1)(x+a)>0(a∈R)。
解:①当a=0时,解集为{x|x<0};
②当a>0时,解集为{x|x<-a或x>};
③当a<0时,解集为{x|}。
心理活动的基本方式是()。
A.反射
B.反馈
C.反映
D.反应
As we all know, tigers and cats________the same family of beasts. [ ]
A. belonged to
B. are belonged to
C. belong to
D. are belonging to