There was a man who had four sons. He hoped his sons could learn not to judge things too quickly. So he gave them a task in turn,____ (ask) them to go to see a pear tree at a distance____(separate).

    The first son set out in winter, the second in spring, the third in summer, and the____young)in autumn.

    When all of them returned home, they were called together____(describe) what they had seen. The first son complained the tree was____ (bend) and ugly. The second son said the tree was covered with buds(花蕾)and full of hope. The third son said it was full of flowers____smelled so sweet and that he had____seen such beautiful scenery. The last son disagreed____all or them, saying it was filled with fruits, full of life and content.

    The man told his four sons that they were all correct, but they only saw the tree in____season, He taught them that the value of a person could only be measure when all the seasons were over.

    If you give up in winter, you____(miss) the hope of spring, the beauty of summer, and the harvest of autumn in your life.

在变电站里，经常要监测电网上的强电流，用到的器材就需要电流互感器．如图所示的四种有关电流互感器的连接方法中，能正确反应其工作原理的是（   ）

根据句意，用所给单词的适当形式填空。
____ He was so tired that he stopped ________(have) a good rest.
____ The girls are old enough, they can take care of ________ (they).
____ Next Thursday is my brother's _______ (twelve) birthday.
____ There are a few _________ (different) between the twins.
____ We must be __________ (care) when we cross the busy street.
____ ______ ______ (事实上) , water covers most of the earth.
____ Kangkang is ______ his mother ______ (带…参观) his school.
____ Taiwan ______ ______ (属于) the PRC.
____ After many years'hard work, her dream ______ ______ (实现) at last.
____ The boy ______ ______ (迷路) and cried on the street.

某生物的长尾对短尾为显性，控制基因为A﹣a，存在胚胎致死效应，假设有两种情况：甲情况为显性基因纯合致死；乙情况为隐性基因纯合致死．下列叙述不正确的是（　　）