题目

短文改错（共10小题；每小题1.5分，共15分） Thank you very much for your letter. I pleased to hear            __________ about your holiday and the people you meet in Rome. It           ___________ sounded great fun and how I wish I could have been with         __________ you. Thank you also for the stamps you sent them to me             __________ for my collection. Most of them were those I had                   ___________ been expecting for long. You said by your letter that               __________ you w夏天，用橡皮膜封闭一锥形瓶的瓶口，把锥形瓶放在冰水中后，瓶口的橡皮膜会向下凹，如图，由此可知：该瓶内气体温度降低，密度    （选择“变大”、“不变”、“变小”）．根据气体密度的这种变化规律，发生火灾时为了避免吸入燃烧后产生的有毒气体，人应尽量贴近地面爬行的理由是    ．