①我被爸爸打了一顿。哭了起来。（改成“把”字句）

②六朝古都南京是一座依江而立的美丽城市。（缩句）

③仔细观察  博览群书  写出佳作（用恰当的关联词连成一句通顺的话）

④他说话很快。（改成比喻句）

铝为什么被誉为“会飞的金属”？

人们常把飞机比成银燕，其实，习机是用铝和铝合金做的．纯铝很软，人们在纯铝中加入4%铜与少量的镁产、锰、硅、铁等，制出了硬铝．由于硬铝既保持了密度小的特性，又克服了纯铝软的特点，因此硬铝很快就成了最重的一种合金．一架普通的飞机，差不多要用50万个硬铝做的铆钉，另外，飞机的外壳、机翼、机尾、螺旋桨、引擎的许多部件也是用硬铝做的．

在金属的家庭中，由于铝的密度小，使它得天独厚地能随飞机一起腾云驾雾，遨游高空，因此被誉为“会飞的金属”．

以前，这个“会飞的金属”，还只能飞翔在地球附近的高空，可是从1957年起，随着人造卫星与宇宙火箭一个个接连上天，铝就成了“飞天”的原材料，前苏联第一颗人造卫星的密封外壳与第二颗人造卫星的动物舱，以及球形容器都是铝合金做的．

本来，铝已经够轻的了，可是1958年以来又研制出了更轻的铝﹣泡沫铝，在泡沫铝的“肚子里”尽是氢气泡，放在水里，它会像木头一样浮起来，1m³的泡沫铝，只有178kg，而1m³的水有1000kg，另外泡沫铝能保温、隔音，不易锈蚀．目前用泡沫铝来做飞机与火箭是最理想的材料．

    Camberwell College Swimming Pools

    Camberwell College of Arts has one 50m (Olympic sized) pool with a depth of 2m throughout, and one 25m pool with a 1m shallow end and a 4m deep end. Both pools may be used by the general public at certain times.

    50m Pool

    The pool is often used for classes, but the general public may use two lanes（泳道）for lane swimming at the following times.

    Monday:        06:30-11:30 and 19:00-21:00

    Tuesday:        06:30-11:30 and 18:00-21:00

    Wednesday:    06:30-13:30 and 17:30-21:30

    Thursday:    06:30-13:30

    Friday:        06:30-13:30

    Weekends:    09:00-17:00

    Children under the age of 14 must be accompanied by an adult.

    Please note that during College holidays, these times will be different. Call 04837 393560 for up-to-date information.

    25m Pool

    The 25m pool is available for recreational (non-lane) swimming from 07:00-09:00 and 12:30-13:30 on weekdays, and 10:00-16:00 on Saturdays.

    Children aged 12 and under must be accompanied.

    We regret that the 25m pool will be closed for redecoration between 21st July and 18th August. The men's changing rooms will be closed for the week beginning 19th August, and the women's changing rooms will be closed the following week. Alternative（可选用的）changing rooms will be made available. We're sorry for this.

中国几千年的封建土地制度被彻底消灭的标志是（    ）