A：把铁块换成铁粉
B：将容器的体积压缩至原体积的一半
C：若保持压强不变，充入氮气使容器的体积增大
D：若保持体积不变，充入氮气使容器内的压强增大
《时代》周刊是美国影响最大的新闻周刊，有世界“史库”之称，它对中国也深入关注。
材料一：1949年2月7日，***第一次（共12次）登上《时代》周刊封面。画面上的***抬头仰望，面带笑容，封面标题为“民主统一”四字。
材料二：这是1971年11月8日的封面，周恩来第三次（共6次）成为《时代》封面人物。左上角写着：“中国人来了”。
材料三：邓小平九次成为《时代》周刊封面人物，这是1979年1月1日的期刊，邓小平又被评为本年度的风云人物。标题写着：“邓小平，中国新时代的形象。”
My father's day
My father is a teacher. He teaches Chinese. He likes his job and his students. And the students like him too. He goes to work from Monday to Friday. He does not work on Saturday and Sunday. Every day, he gets up at five thirty. At six, he has breakfast. Then he goes running. He goes to school at seven. He has lunch at school. He goes home at five in the afternoon. At six o'clock, he has dinner. He doesn't watch TV. He likes reading（读）books with me. He goes to bed at nine thirty.
溶质的质量分数= ____ ，溶质的质量=____ ．
下列关于变异的叙述，正确的是（ ）
