题目

回答问题， My children are growing up fast. My daughter is 16 and my boy is already in junior high school. As they get bigger our house seems to get smaller. So we want to sell some of our things in a yard sale and give the mony to a children’s home.  We have already cleaned out a lot of things from our bedrooms. We have decided to each sell five things that we no longer use. My son was quite sad at first. Although he has not played with his old toys for a long time, he still wanted to keep them.  for example, he has owned a train and a railway set since his fourth birthday, a根据下面提供的资料，回答问题：森林是全球50%-90%的陆生生物的家园，目前全世界只剩下五分之一．两千年前我国森林覆盖率在50%，而今天仅为16.55%．藏羚羊是我国一级保护动物．1986年在西藏、新疆、青海三省栖息，平均每平方公里有3头至5头，到20世纪90年代平均仅有0.2头．近年来，捕猎者的枪声不断．武汉市东湖在1970年至2000年，由于生活污水排入等原因，水底生活的动物种类由113种减到了26种．为了净化污水，我国的云南滇池引进水葫芦后（国外引进的物种），由于水质污染导致它疯长，遮盖了整个滇池，很多水生生物几乎绝迹．（1）指出造成生物多样性受到威胁有哪些原因？（要求不少于2种） ．（2）进入20世纪后，几乎每年至少有一种鸟类或哺乳动物从地球上消失，造成野生动物濒危或绝灭的主要原因是 ．A、自然灾害        B、天敌过多     C、生态环境被破坏     D、动物瘟疫（3）保护生物多样性最有效的措施是 ．（4）生物多样性不包括 ．A、生物数量的多样性    B、生物基因的多样性   C、生态系统的多样性    D、生物种类的多样性．