题干

将具有一对相对性状的纯种豌豆个体间行种植;另将具有一对相对性状的纯种玉米个体间行种植。具有隐性性状的一行植株上所产生的F1是(  )

A:豌豆和玉米都有显性个体和隐性个体

B:豌豆都为隐性个体,玉米既有显性又有隐性

C:豌豆和玉米的显性和隐性比例都是3∶1

D:玉米都为隐性个体,豌豆既有显性又有隐性

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答案(点此获取答案解析)

B

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阅读理解

B

    Many blind people use guide dogs to help them get safety from place to place and to warn them of danger. But what can blind people do if they are allergic(过敏的)to dogs or just don't like them? For some people, the answer is provided by the Guide Horse Foundation.

    Janet and Don Burleson founded the organization in 1999. They began training miniature horses to help guide blind people. Miniature horses look just like regular horses, only much smaller. They are generally less than 34 inches tall.

    Cuddles was the foundation's first guide horse in full service(服务). She became 45-year-old Dan Shaw's helper. Shaw has an eye disease and his sight is very poor. One night, while filling out a form to get a guide dog, Shaw heard a news story on TV about people training horses to guide the blind. Shaw loves horses and wanted a guide animal that would live a long time. He applied(申请), and a year later, Cuddles and Shaw began training as a team.

    On a trip to New York, Cuddles helped Shaw safely tour Times Square, a very busy part of the city at night. The next day, Cuddles calmly rode the elevator with Shaw to the crowded top of the Empire State Building, a famous tall building. Cuddles even guided Shaw on the boat ride to the Statue of Liberty(自由女神像), and traveled on the subway system.

Shaw says that he is very lucky to have Cuddles. He believes that Cuddles has changed his life for the better by giving him more freedom.