An epidemic is the name given to an     1     （infect）disease that rapidly spreads to a large number of people within a short period of time-usually two weeks or less. It can     2     （cause）by several different factors, such as a virus being carried into an area, changes in the way people live,     3     increases the chances of them coming into contact with a bacteria or virus.

Teenagers in the U. S. know they'll probably need tech skills     1     (land)good jobs, but a new survey     2     (suggest)that interest in tech careers may be decreasing.

The percentage of boys aged 13 to 17 who are interested in science, technology, engineering and math-or STEM-careers dropped according to a survey by Junior Achievement USA. The amount of girls     3     (interest)in STEM careers stayed unchanged at 11 percent.

Don Stephenson used to live in the streets a few years ago. He was homeless and poor. “I didn’t know     1     my next meal was coming from,” he says. Now Stephenson has a home and makes a living as a mechanic. But he has not forgotten the people in the streets. One night a week he goes to the poor side of the town. He stands on street corners and hands out $5 or $10 to anyone     2     needs it. In addition, he gives away food and clothing. “I don’t want to see anyone     3     (hunger),” he says. “I understand these people because I     4     (be) there.”

After a two-week-long trip to China, Dar became a skillful user of WeChat, an application that almost every Chinese would use in their daily life. During his stay in Beijing, Dar     1     (recommend) his family and friends to download WeChat so that they could contact through free WeChat video calls. And via the function of translation, Dar found it easy and efficient     2     (understand) what his friends were saying. As one of the many Chinese innovations nowadays, WeChat is only a glimpse of the energy and     3     (create) in today’s China.

Smartphones are becoming more and more of a necessity for high school students. Therefore, a discussion was held about     1     the senior school students should use our smartphones at school. People     2     (support) the idea consider it convenient to contact the students’ parents when necessary. However, people who are against it find some students are addicted to playing the smartphones easily,     3     effect on their studies is quite worrying. It is even     4     (bad) that smartphones can also discourage students’ will.

One day, a man found the pupa (蛹) of a butterfly.     1     (see) an opening in the pupa, he realized that the butterfly was ready to emerge. So he sat down and watched as the butterfly struggled to force its body     2     the little hole. However, minutes passed and the butterfly still couldn’t get out. The struggle was too hard for its weak body. The man then     3     (kind) enlarged the hole in the pupa so that the butterfly could finally break free. But instead of flying away, it just dragged itself around weakly, then died. The struggle to break out of the pupa was necessary for the butterfly’s survival     4     it enabled its wings and body to grow strong. Without the struggle, it was too weak to live.

Parents these days seem to protect their children more than ever before. And yet the truth is that children must     1     (give) the opportunity to take risks in order to aid their development. By the time a child becomes an adult, he needs to learn     2     they can deal with the success and failure connected with risk-taking. It is a real shame that nowadays there are many children     3     (miss) out on typical childhood activities such as tree climbing. That is mostly because of their parents’ fear of     4     (injure), especially as many of those parents may have enjoyed such activities when they were growing up.

Evan is a wildlife photographer. Once, two tigers     1     (run) past him, stopped a meter away from his truck and began to fight. He was too afraid to photograph them. Another time in Namibia, one lion came even     2     (close). It went all the way round his truck. Then it got up on the back and looked at him     3     the window, which was one of his happiest moments. Evan’s pictures make people think about animals in danger, which matters a great deal to him.