白化病的祖辈一定有人患白化病，他的子女也一定会患白化病。（ ）
错
题目分析：白化病属于家族遗传性疾病，为常染色体隐性遗传，常发生于近亲结婚的人群中，
其遗传图解是：
可见白化病的祖辈不一定有人患白化病，他的子女也不一定会患白化病，如果和正常人结婚，则不会患病。
点评：此题为基础题，解答此题的关键是掌握并理解基因的显性和隐性以及它们与性状表现之间的关系，可结合遗传图解进行解题。
| 阅读下面短文，掌握其大意。然后从A、B、C、D四个选项中选出最佳选项。 | ||||
| Many scientists say that the world is getting hotter and hotter. If they are right, the ice at the North and South Pole will melt eventually. If this happens, the sea will rise and may cover most 1 all of Singapore. This will force everybody to move to a 2 country. We know that the sun 3 the earth. The heat from the sun hits the 4 , and some of it goes back into the sky. However, factories and cars 5 a lot of carbon dioxide (二氧化碳). When the gas rises into the sky, the heat from the sun can come 6 them but the heat from the ground cannot. It 7 near us in the sky and makes the 8 hotter and hotter every year. Scientists call this the "greenhouse effect" because a greenhouse is a small glass 9 which is hot inside. It is used for growing plants in cool countries. Many countries are 10 about the greenhouse effect. They are trying to stop factories and cars from sending 11 gases into the sky. Scientists are not sure when the world will get much hotter. Some people say that the greenhouse effect has 12 already and has begun to affect the world's weather. | ||||
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