I often ______ my homework _______ 7:00 in the morning.[ ]

A. do, in            

B. does, at          

C. do, at

下列各函数中为奇函数的是  [ ]

A.y=x+3  

B.y=x²+x  

C.y=|x﹣1|﹣|x+1|  

D.y=﹣|x|