A:x2﹣ y23 =1
B:y2﹣ x23 =1
C:x2﹣y2=2
D:y2﹣x2=2
已知函数fx=1-2x,x≥02x-1,x<0,则该函数是( )
The food safety is a serious _______ in our country. We should try to solve it.
某物体的位移﹣时间图象如图所示,下列说法中正确的是( )