听力原文：

For thousands of years, people used different ways to measure things. Some people measured things using the size of their king’s foot or hand. When the king died, they used the new king’s foot, and so on. This wasn’t a good way to measure things. People all over the world used the Sun and the Moon to measure time. However, they all had different numbers of days in a week and different numbers of hours in a day. In 1584, one of the scientists started to think about a set of measures, which used the number ten, but no one was interested in his ideas. In about 1785, many scientists decided to use meters to measure length and they worked out how long a meter should be.

Question: When did scientists decide to use meters to measure length?

参考答案：

In about 1785.