题目内容：

Many people go to school for an education. They learn languages, history, politics, geography, physics, chemistry and mathematics. Others go to school to learn a skill so that they can make a living. School education is very important and useful. Yet, no one can learn everything from school. A teacher, no matter how much he knows, can not teach his students everything they want to know. The teacher’s job is to show his students how to learn. He teaches them how to read and how to think. So, much more is to be learned outside school by the students themselves.

It is always more important to know how to study by oneself than to memorize some facts or a formula(公式). It is actually quite easy to learn a certain fact in history or a formula in mathematics. But it is very difficult to use a formula in working out a math problem. Great scientists before us didn’t get everything from school .Their teachers only showed them the way. Edison did not even finish primary school. But they were all so successful. They invented so many things for mankind. The reason for their success is that they knew how to study. They read books that were not taught at school . They would ask many questions as they read. They did thousands of experiments. They worked hard all their lives, wasting not a single moment. Above all , they knew how to use their brain.

1. To work out a math problem, you need to know __________.

A．only a certain formula

B．how to memorize some facts

C．only some facts

D．the method to work it out

2. Why were many scientists so successful?

A．They received good education.

B．They were very clever.

C．They knew how to learn.

D．They learned lots of facts and formulas.

3.How did great scientists study?

A．They read a lot of books and asked many questions while reading.

B．They did thousands of experiments.

C．They always worked hard and never wasted time.

D．All of the above.