两点可以确定一条线段,在一条直线上取20个点,最多可以确定 条线段.
涂一涂,算一算,填一填.(1) + = + = (2) ﹣ = ﹣ = .
我会填.(1)== ;(2)=﹣= .
在横线里填上合适的数.(1)+ =(2)+ =1(3)﹣ =(4) ﹣=0.
看图写算式.(1) + + = . × = (2) + = = . × = = (3) + + + = . × = .
+=+= . (判断对错)