2. 70 cups become 30 cups.

3, 30 cups 100.

4, 70 into 30, at this time there is 10 ml in the cup of 70.

5. Pour 10 ml of water into 30 cups.

6. At this time, there is only 90 ml in 100. 70, 100, 20 ml left.

7. Pour 30 into 100 and add the original 20 ml to make 50 ml.

Unit conversion

1L = 1000ml 1000ml = 1000 m3？ = 1 cubic decimeter

1 ml = 1 ml.

1 ml liquid water = 1 cm3 liquid water

1 ml The weight of liquid water at 4 degrees Celsius is 1 g.

1 ml = 1 cm3