(1)4千米=4000米;
(2)6000千克=6吨;
(3)7厘米=70毫米;
(4)5吨=5000千克;
(5)200厘米=2米;
(6)20分米=2米;
(7)1米-6分米=4分米;
(8)4吨+2000千克=6吨.
故答案为:4000,6,70,5000,2,2,4,6.
(1)4千米=4000米;
(2)6000千克=6吨;
(3)7厘米=70毫米;
(4)5吨=5000千克;
(5)200厘米=2米;
(6)20分米=2米;
(7)1米-6分米=4分米;
(8)4吨+2000千克=6吨.
故答案为:4000,6,70,5000,2,2,4,6.