3 次の文章を読んで、あとの (1) から (5)までの問いに答えなさい。 The world is a very wonderful and interesting place that is full of nature. Plants and animals have important parts in the ecosystem. Even small insects have their own roles. Do you know that over 60% of all the known species on the earth are insects? That's true. Many studies are (A) and scientists are getting worried about the results. According to a study in Germany, over 75% of flying insects have decreased. There are many reasons, such as air pollution, water pollution, ground pollution, a lot of chemicals to save plants, and so on.