根据短文理解，选择正确答案。

    Winter-swimming has become popular in Beijing. Three years ago, few people would go swimming in the city waters. But now there is a Winter-swimming Enthusiasts' Club(冬泳爱好者协会)and it has more than 2,000 members. The oldest is 84 years of age and the youngest is only 7. The members are from all ways of life__They may be workers, peasants, soldiers, teachers, students...

    Though it is now the coldest part of the season and the water temperature in the city's lakes is around 0°C, many winter-swimmers still swim in the icy waters, even when it is snowing. They enjoy themselves in the lake, while the people by the side of the lake are wearing heavy clothes.

    Why are so many people interested in winter-swimming? Because winter-swimming can be good for one's health.

    Bei Sha is a good example. He is 69 years old, and he once suffered from heart trouble for 26 years. After ten years of winter-swimming he is now in good health.

    Scientists are now studying the effects of winter-swimming on health.

据清通州（今南通）人刘长华《梓里述闻》记载，道光二十二年（1842年），英国舰队侵入长江以后，一直开到南京。军舰来往于南通江面时，当地人惟恐英军登陆，纷纷下乡避难。该记载反映的侵略战争是（    ）

普通自行车上，通过增大压力来增大摩擦的装置是 ____ ；在前后轮中减小摩擦的措施是在轮子的轴上安装了 ____ 。