题干

华南虎和东北虎两个亚种(属于同一物种)的形成是由于(  )

A:地理隔离

B:生殖隔离

C:地理隔离和生殖隔离

D:基因突变和基因重组

上一题 下一题 0.0难度 选择题 更新时间:2016-03-07 05:12:02

答案(点此获取答案解析)

A

同类题2

阅读下面短文,掌握大意,然后从A、B、C、D四个选项中选出最佳选项。

    It does not always come easy to discover oneself. From a young age, I had a strong sense of who I was to become, 1 an accident made me redefine (重审)myself.

    To me, skating was above all. There was 2 in this world that filled my heart with such joy. I spent twenty-four hours a week practicing my  3  . Having no social life or interests but skating, my devotion( 挚爱) brought me first place medals in nearly every 4.

    Unfortunately, in one show, I fell down and hurt myself 5. After several X-rays and MRI(磁共振)scans, the 6(told)me that I couldn't return to my sport any more. The pain in my back was hard to bear and even the 7 daily tasks became difficult.

    As my passion(激情)was 8, I had little sense of who I was to become. After eight months of suffering, something had to 9. Instead of wasting my days sitting around painfully, I began to put my 10 into local community service projects. By volunteering 11 a swimming teacher and summer reading assistant for kids, I got an idea of who I 12 to become. After a few months, I devoted time to my interest in the arts. Little by Little, I 13 out of the shadow( 阴影)and rebuilt my confidence.

    Sometimes, some 14 rocks block (阻碍)our way. We can choose to stay behind or try to climb over. My accident was a rock that 15 to stop me from reaching success. Today I'm a very confident and optimistic person.