4. 你在此时放弃是不明智的。

It's not at this moment.

3. 近来人们谈论最多的话题是关于环境问题。

The hottest topic that people are these days is about environmental problems.

2. 成绩的好坏取决于你是否努力。

Good or bad grades whether you are hard-working or not.

1. 人们可以通过循环利用来节约资源。

People can save resources .

6. The work is going to be finished in two days.(改为否定句)

The work be finished in two days.

5. I am given a birthday present by my parents every year.(同义句转换)

A birthday present by my parents every year.

4. You should pay attention to your pronunciation in learning English.(改为被动语态)

Attention should   to your pronunciation in learning English by you.

3. They grow rice in South China.(改为被动语态)

Rice   in South China by them.

2. Where do people plant the trees?(改为被动语态)

Where  the trees  by people?

1. People speak English widely in the world.(改为被动语态)

English   widely in the world by people.