Lesson 53 Hot snake

At last firemen have put out a big forest fire in California. Since then, they have been trying to find out how the fire began. Forest fires are often caused by broken glass or by cigarette ends which people carelessly throw away. Yesterday the firemen examined the ground carefully, but were not able to find any broken glass. They were also quite sure that a cigarette end did not start the fire. This morning, however, a fireman accidentally discovered the cause. He noticed the remains of a snake which was wound round the electric wires of a 16,000-volt power line. In this way, he was able to solve the mystery. The explanation was simple but very unusual. A bird had snatched up the snake from the ground and then dropped it on to the wires. The snake then wound itself round the wires. When it did so, it sent sparks down to the ground and these immediately started a fire.

消防队员们终于扑灭了加利福尼亚的一场森林大火。从那时起，他们一直试图找出起火的原因。森林火灾时常由破碎的玻璃或人们随手扔掉的香烟头引起。昨天，消防队员仔细查看了地面，但未能发现碎玻璃。他们还十分肯定火灾也不是由烟头引起的。然而今天上午，一个消防队员偶然发现了起火的原因。他发现了缠绕在16,000伏高压线上的一条死蛇。就这样，他解开了起火之谜。解释很简单，却异乎寻常。一只鸟把蛇从地上抓起来，然后把它扔到了电线上。于是蛇就缠住了几根电线。当它这样做时，把火花送到了地面，这些火花立刻引起了一场大火。

Grammar

1. 定语从句与宾语从句

2. 动词时态：过去完成时，现在完成进行时

宾语从句最常见的考察形式就是直接引语转间接引语，注意人称和时态的变化。人称变化口诀是：一随主，二随宾，三不变； 时态变化则要视情况进行变化。

Exercise

1. I __________ them not everybody could run as fast as you did.

A. have been telling   B. have told        

C. had told           D. told

2. Tom _________ the electronics since he__________school ten years ago.

A. studied; entered       B. has been studying; entered

C. has been studying; has entered      D. has studied; has entered

解析：1. 答案：D. 考查主从句时态一致，后半句使用过去时could，则前半句也使用一般过去时。

2. 答案：B. 考查since的用法。since常与完成时连用，但since后需要用过去的时间状语或者过去时的句子，本题答案为: has been studying, left.