Bai 3

1, You can go home because you’ve finished this exercise.

2, I don’t get many opportunities to practice my English; therefore, I find it difficult to remember everything I study.

3, I’m practicing speaking English a lot because I don’t want to fail in the oral test.

4, The world’s energy resource is limited, so we should use them economically.

5, The country will face an energy crisis if demand continues to rise.

Bai 4:

1, You can’t borrow my dictionary unless you bring it back on Monday.

2, Solar domestic heating systems are economical to use but the cost of installation is very high.

3, Solar panel are placed on the roof of a house and the Sun’s energy is used to heat water.

4, I don’t agree with a lot of his teaching methods; however, he is a good teacher.

5, We’d better not waste water, or we won’t have enough to drink sooner or later.