43291000000≈____亿
935450000000≈____亿
如图,△ABC≌△DEF,△ABC的周长是40cm,AB=10cm,BC=16cm,求△DEF中,边DF的长度.
“日出而作”,“守望相助”是成语。( )
My father usually____(go)to work by bus,but he____(drive)his car to work yesterday