the number of，In order to，think of，call on，died out

When people（1）

think of

think of

tigers，they think they are strong and dangerous.But now，the big animal is calling for our help.There were once eight kinds of tigers in the world，but three of them（2）

died out

died out

during the 20th century.In the last 70 years，（3）

the number of

the number of

Siberian tigers （東北虎）has gone from as many as 300 to less than 22 somewhere.The Siberian tiger has been in danger of dying out completely.If the government doesn't make any efforts，it's quite possible that there will be no more Siberian tigers in China in ten to twenty years.
    （4）

In order to

In order to

double the number of wild tigers in the next ten years，the World Wildlife Fund has started a program recently.It aims to save wild tigers and put an end to tiger hunting and killing.China，together with twelve other countries，has joined in.
    Wild animals，such as red deer and wild pigs，are the main food of the tigers，The hunting of these animals is the greatest threat（危險） to tigers.So the most important thing is to save the animals that tigers eat.To protect the wild tigers，we need to（5）

call on

call on

more people to stop eating and hunting wild animals.