④Water can carry_away the soil only if it is flowing fast.

　　水只有在流得很快的时候才能带走泥土。

　　5．(教材P55)It was fortunate that the US Navy's aircraft carriers were at sea that day.

　　幸运的是美国海军的航空母舰那天在海上。

　　fortunate adj.　幸运的

　　①I am fortunate that I have Prof.Smith guide me in my research.

　　我有幸由史密斯教授指导我的研究。

　　(1)be/feel fortunate to do sth.　　有幸做某事

　　be/feel fortunate in (doing) sth. 在......方面很幸运

　　It is fortunate that ... ......是幸运的

　　(2)fortune n. [U]机会；运气

　　 [C]大笔的钱

　　seek one's fortune 找出路

　　tell one's fortune 为某人算命

　　try one's fortune 碰运气

　　②I am fortunate to be chosen for a trip abroad.

　　我真幸运，被选中出国旅行。

　　③It_is_fortunate_that nobody was injured in the accident.

　　在事故当中无人受伤真是万幸。

　　④Many young people in the village leave for big cities to seek_their_fortune nowadays.

　　现在，很多年轻人离家到大城市找出路。

　　6．(教材P55)The next day, US President Franklin Roosevelt declared war against Japan.

　　第二天，美国总统富兰克林·罗斯福向日本宣战。

　　declare vt.　宣布，宣告，宣称

　　①He declared his intention to become the best actor in the world.

　　他宣布了自己要成为世界上最出色的演员的意图。

　　declare that ...　　　　　　 　声明/宣布......

　　declare war against/on ... 向/对......宣战

　　declare for/against sb./sth. 声明赞成/反对......

　　declare sb./sth.(to be)＋adj. 声称某人/某事......

　　②We declare that these decisions shall not be carried into practice.

　　我们宣布这些决议将不执行。

　　③The city council has declared for improving the public bus system.

　　该市议会宣布同意改进公共汽车系统。

　　④She declared herself extremely hurt by lack of his support.

　　她说自己非常伤心，因为没有得到他的支持。

　　[辨析比较]　

declare 常用于正式场合，指清楚、有力地宣布，公开地让人知道；常用于宣战、议和或宣判，可接复合宾语 announce 指把人们关心或感兴趣的事正式公布于众，尤指新闻，不能跟双宾语 　　选择上述单词填空

　　①It has been announced that the flight will be delayed.

　　②They declared him the winner.

　　③He declared himself strongly in favour of the project.

7．(教材P55)In memory of the Americans who died in the attack, a national memorial was built in Pearl Harbor just above the remains of the Arizona.