36. A an explosion ( Dòng 2: An eruption can like an explosion )
37. D All above ( Rock and lava can throw up into the air. The air is filled with deadly gases. )
38. B scientists ( Dòng 4, 5 )
39. D 4
- They can study the movements of the ground.
- Scientists can also measure the gases that come out of a volcano.
- They can also study the way the land and water around the volcano.
- Scientists can read these signs and warn people of danger.
40. A ( Dòng 6 )