语法填空Animals can become endangered for a number of reasons,but many experts believe that loss of habitat is the main cause.Some animals are put 1. ____danger when people take over their habitats.This often 2. _____(occur) because people want one or more of the resources (资源) in those areas.Some forests,for example,provide wood 3. ____is used for things like paper and furniture,etc.Many trees 4. ____(cut) down every day for such purposes but not enough are being planted.It has seriously decreased the population of many species.In some cases,loss of habitat arises from forest fires or flooding of land.Environmentalists and zoologists are 5. _____(frequent) trying to do what they can to prevent the number of populations from 6. _______(drop) too seriously.Sometimes,people influence nature,indirectly causing the animals 7. _____(lose) their habitats.Experts believe the problem is becoming much 8. ____(bad) because of the emission (排放) of greenhouse gases.They don't know 9. ____much influence people have,however.The greenhouse effect can also influence weather 10. _______(pattern) that affect animals.