You may not like insects(昆虫), but all life on earth needs them to live. Birds, fish and many other small animals feed on insects.①如果没有昆虫，它们会死。As they die, other larger animals which eat birds, fish and small animals will die, too. It will lead to mass extinction(大灭绝). What's more, insects pollinate(给...授粉) most plants. That means people cannot grow crops(庄稼)②_____________ them.
Insects are very important, so it is a great surprise when a new study shows that the number of insects is falling by 2.5 percent a year. If the number keeps on falling like this, there will be 75 percent of insects' left③ _____________ just 10 years. ④If that happens, all life will be in great danger.
Why are there fewer and fewer insects? There are two answers to this question. It is probably because of earth's rising temperature. It may be because of the use of chemicals(化学品)in farming. In either situation, it's time for human beings to do something to solve the problem.
