以前的生活很简单，人们不会制造出太多的废气，对地球也没有那么大的伤害。

Life in the past was very simple, people did not produce too much exhaust gas, and did not cause so much harm to the earth. In general, I think it was better in the past, because it is convenient for human beings, but its impact on the environment is very bad.

Life was simple before, people wouldn't make too much exhaust gas, and they wouldn't do so much harm to the earth. Overall I think it's better than it used to be, because it's convenient for humans now but the impact on the environment is bad.

Life used to be simple. People didn't produce too much waste gas and didn't do so much harm to the earth. Generally speaking, I think it's better than before, because it's convenient for human beings now, but its impact on the environment is very bad.