Unit 4　Astronomy:the science of the stars

Period 2　知识讲练课

学习目标

　　1.Master the usages of such important words and expressions as:exist,puzzle,in time,in one's turn,prevent...from,cheer up,break out,watch out;learn to express yourself by using them.

　　2.Learn the method of constructing knowledge trees through self-study and cooperative exploration.

　　3.Enjoy the fun of expressing yourself by using English and participate in class with a strong passion.

课堂探究

　　一、词汇精粹

　　学习建议:根据所列例句,理解并尝试总结下列词汇的用法。

　　1.exist vi.存在;生存

　　【教材原句】 They laid eggs too and existed on the earth for more than 140 million years.它们也生蛋,在地球上生存了一亿四千多万年。

　　【观察思考】

　　(1)Fish can't exist out of water.鱼离开了水无法生存。

　　(2)Do you believe the existence of ghosts?Perhaps they only exist in some people's imagination.

　　你相信鬼魂的存在吗?或许他们只存在于一些人的想象里。

　　(3)The hostages (人质)existed on bread and water.人质靠水和面包生存。

　　(4)There exist many ancient temples of this kind on the shores of the Mediterranean.

　　在地中海沿岸地带,有许多这样的古庙。

　　(5)As time went on,the small town came into existence.

　　随着时间的流逝,这个小城镇形成了。

exist vi.存在;生存

(1)存在于......　　　　　　　

(2)靠......为生　　　　　　　

(3)某地存在......　　　　　　　

(4)开始存在;成立　　　　　　　

　　2.puzzle n.谜;难题　vt.&vi.(使)迷惑;(使)为难

　　【教材原句】 How life began on earth is one of the biggest puzzles that scientists found hard to solve.地球上的生命是如何起源的是科学家们最难以解答的问题之一。

　　【观察思考】

　　(1)What puzzles me was why they didn't take her advice.

　　使我大惑不解的是他们为什么没有接受她的建议。

　　(2)They puzzled over the question for quite a while.

这问题他们苦苦思索了很久。