It was not until the 18th century that man realized that the whole of the brain was involved in the working of the mind，　　　　？

A.was it               B.wasn’t it            C.did they                        D.didn’t they

It was not until the 18th century that man realized that the whole of the brain was involved in the working of the mind， 　　　　？

A.was it     B.wasn’t it    C.did they   D.didn’t they

It is clear that the whole world is passing through a social revolution in which a central _____ must be taken by scientists and technologists.

　　A. process   B. attention    C. measure    D. part

Too many cars have created a lot of serious problems in our world. Besides congestion(拥塞), accidents and fast fuel consumption(消费), cars are responsible for a good part of air pollution in big cities. All the time, they are pumping huge amounts of waste gases into the atmosphere. These gases are very harmful, causing disease and even death. Last winter, car fumes(烟雾) formed heavy smog over Beijing, making the sky gloomy for weeks and deteriorating people's health.

One possible solution is to design and develop clean cars and clean fuels. In Tsinghua University, campus buses are driven by electricity. In Beijing some of the public buses begin to run on natural gas, which does not give off as much carbon dioxide as the petrol. But it may take decades for the new models of clean cars to completely replace the traditional ones.

Another solution is to develop modern public transportation systems and restrict （限制）the use of private cars. If the price of petrol rises constantly and the public vehicles（交通车辆） are efficient and convenient enough, most people will not use private cars. And the total number of cars in big cities will reduce greatly. 　　

On the whole, the elimination （根除）of air pollution needs the co-efforts from the government, the public and the environments. This problem will be solved only with the help of science and technology.

1.What is the main reason for air pollution in big cities?

2.What is the best title of this passage?                               

3.How many ways are mentioned to solve the pollution caused by cars?      

4.Which of the following is TRUE according to the passage?               

  ______ students in class 4 took park in that spring outing.

　 A. 48 all 　 B. 48 whole   C. All 48 　 D. The whole 48