Read the following passage, and mark the letter (A, B, C or D) on your answer sheet to indicate the correct answer for each of the blanks.Wind, water, air, ice and heat all work to cause erosion. As the wind blows over the land, it often (31)________ small grains of sand. When these grains of sand strike against solid rocks, the rocks are slowly worn away. In this way even very hard rocks are worn away by the wind. When particles of rocks or soil became loosened(tơi ra) in any way, running water ...

Read the following passage, and mark the letter (A, B, C or D) on your answer sheet to indicate the correct answer for each of the blanks.

Wind, water, air, ice and heat all work to cause erosion. As the wind blows over the land, it often (31)________ small grains of sand. When these grains of sand strike against solid rocks, the rocks are slowly worn away. In this way even very hard rocks are worn away by the wind. When particles of rocks or soil became loosened(tơi ra) in any way, running water carries them down the (32)________ Some rocks and soil particles are carried into streams and then into the sea. Land that is covered with trees, grass and other plants wears away very slowly, and so loses very (33)________ of its soil. The roots of plants help to (34)________ the rocks and soil in place. Water that falls on grasslands runs away more slowly than water that falls on bare ground. Thus, forests and grasslands (35)________ to slow down erosion.

Điền vào ô số 33