What is    1    （友谊）? It implies    2    （忠诚）,     3    （同情），affection, and     4    （乐意）to help. Friendship is like sunshine. It brings us     5    （热情）and     6    （幸福）. If you are in trouble, your friends will help you or     7    （鼓励）you. When you are happy, they     8     （分享）your pleasure with you. You could be having the worst day of your life, and they would still make you laugh. Friendship is also one of the greatest pleasures that we can enjoy. In order to develop and keep our friendship, we should learn to communicate with others properly, to be a good listener and to be     9    （诚实的）and     10    （坦率的）. Most importantly, we need to have a correct understanding of friendship.

Many animals move from one place to another at certain times of the years,     1     is called migration. They migrate to find food, seek a partner, or in search of warmer weather.

Every autumn,     2    （million）of the North American monarch butterflies begin a long and difficult journey. They manage to travel around 4,000 kilometers south and get to California or Mexico. However, how they did this was unclear.

A team of scientist has now found that the monarch is able to tell the time of day. It uses its eyes     3    （measure）the position of the sun. It uses the time of day and the point of the sun to determine the way to go and change its     4    （direct）. Eventually, it manages to reach the place     5     it will spend the winter.

In the last few years its population     6    （crash）significantly.     7    （sad），human activity is the main reason why the number of monarch butterflies is falling.

People cut     8     trees and use chemicals, which destroys the natural environment.

The research on the monarch’s behaviour has lead to a greater     9    （aware）of this creature. There may come a time when the number of monarch butterflies increases once again. The     10    （much）we know about this lovely creature, the greater the chance it will survive.