题目

Expo’99 Kunming hosted by the Chinese Government between May 1, and October 31,1999 was the last of same kind of international expositions（博览会） in the 20th Century. The theme（主题） of the exposition was “Man and Nature—Marching into the 21th Century”.    Expo’99 Kunming contained mainly five halls, such as the Hall of Man and Nature, the Hall of Science and Technology, the International Hall, the Greenhouse Hall and the China Hall. There were also six gardens in the venue, including the Trees Garden, the Herbal Plants Garden, the Potted Landscaping Garden, th我国法律禁止近亲结婚的理由是______。A．近亲结婚使其后代获得相同致病基因的可能性大B．近亲结婚造成显性基因控制的性状出现的频率高C．近亲结婚生育的孩子都不容易得遗传病D．近亲结婚会造成后代不育