51, Fewer students are willing to work in rural areas after graduate.

Fewer students are willing to work in rural areas after graduation.

52, I have many works to do today.

I have much work to do today.

53, A new means of teaching is being used in that school.

54, Governments should take the responsible for air pollution.

Governments should take the responsibility for reducing air pollution.

55, Fossil fuels are important to economy and society development. Especially to these developing countries.（不知道有什么问题）

Fossil fuels are important to economic and social development, especially to these developing countries.

56, Students can get a lot of experiences during the gap year

Students can get a lot of experience during the gap year.

57, There were a lot of people who worked in this factory.

A lot of people work in this factory.