A man was traveling abroad in a small red car. One day he left the car and went shopping. When he came back, its roof was badly damaged.

    Some boys told him that an elephant had damaged it. The man did not believe them, but they took him to a circus(马戏团) which was near there. The owner of the elephant said, “I am very sorry! My elephant has a big, round, red chair. He thought that your car was his chair, and he sat on it!"

    Then he gave the man a letter, in which he said that he was sorry and that he would pay for all the damage.

    When the man got back to his own country, the customs（海关） officers wouldn't believe his story. They said, “You sold your new car while you were abroad（国外） and bought this old one!"

    It was only when the man showed them the letter from the circus man that believed him.

如图所示，把一个底端密闭的薄壁金属管固定在桌上，管里放一些酒精，管口用塞子塞紧，用绳子在管外绕几圈并迅速地来回拉动，一会看到塞子被弹起。

下列关于测量的说法中不正确的是（    ）

胡绳在《***的七十年》中说：“从大革命失败到全国抗日战争开始前夕这十年，是***在极端困难的条件下坚持斗争并达到政治上成熟的时间。”这一时期***政治上“成熟”的表现是（      ）
①实现国共合作，进行北伐战争

②探索出一条以农村包围城市的革命道路

③召开遵义会议，事实上确立了***为核心的党中央的正确领导

④制定了全面抗战路线

下列关于性染色体的叙述，正确的是(   )