一、认真填一填 (每空 2分 ,计 3 6分 )1 .-1的相反数等于 ,绝对值等于 2的数有 .2 .一艘潜艇在水面下 50m ,记作 -50m ,在这艘潜艇的正上方 2 0m处有一只鲨鱼 ,则这只鲨鱼的高度可以表示为m .3 .请写出与 2xy是同类项的任意两个单项式.4.如图 ,从学校到书店最近的路线是 ( 1 ) First, carefully fill in one (2 points per space, count 36 points). The inverse of 1.-1 is equal to the number of absolute values ​​equal to 2. There is a submarine of 50 meters below the water surface, recorded as -50m. There is a shark 20m directly above the submarine. The height of the shark can be expressed as m.3. Please write any two monomials that are the same type of items as 2xy. Figure 4. From school to bookstore The route is (1)