小明自己制作了一个哨子，如图所示．在筷子上缠一些棉花，做成一个活塞，用水蘸湿棉花后插入两端开口的塑料管．吹管的上端，可以发出悦耳的哨声．这哨声是由管内空气柱 ____产生的．上下推拉活塞，可以改变声音的 ____（选填“音调”，“响度”，或“音色”）．

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《红楼梦》里黛玉与宝钗的对比鲜明。黛玉常以妒心待人，心怀疑虑，多愁善感，终究红颜薄命；宝钗大方贤淑，宽容乐观，深受贾母和他人的喜欢。这说明（   ）
①宽容别人，别人才会悦纳自己，保持良好心态②缺乏爱心，会导致人际关系恶化，影响身体健康
③宽容别人，是保持乐观心态的唯一途径          ④宽容别人，容易受到伤害，不利于保持乐观心态

    Most Chinese eat three meals a day. In the past,they had breakfast in the morning, a big lunch at noon, and a light supper at night.

    But now both men and women in the big cities have to work on the weekdays. So they often eat bread, eggs, milk and porridge forbreakfast at home. For lunch, Chinese take-away food is very popular. They often have a quick lunch in their workplaces.

    After work in the afternoon, they have more time for supper. They usually eat a big meal at home. Wives often cook meat, fish, chicken, vegetables and rice for their family.You can also find dumplings and noodles on the table in most families of northern(北方的)China.