—Tina, I have cleaned most of the windows.—That's very kind ___ you. It's difficult me to do it all by myself.
A:of; for
B:for; of
C:for; for
D:of; of
读诗《乞巧》《嫦娥》选择合适的解释。
A、 用云母做的屏风 B、 古代的节日,又名七夕 C、银河,天河 D、浩瀚无际的青天 E、今夜
今宵____
碧霄____
云母屏风____
乞巧____
长河____
已知函数f(x)=﹣x2+ax+b2﹣b+1,(a,b∈R)对任意实数x都有f(1﹣x)=f(1+x)成立,若当x∈﹣1,1时,f(x)>0恒成立,则b的取值范围是( )