Who doesn’t love sitting beside a cosy fire on a cold winter’s night ? Who doesn’t love to watch flames (火苗) curling up a chimney? Fire is one of man’s greatest friends, but also one of his greatest enemies. Many big fires are caused by carelessness. A lighted cigarette thrown out of a car or train window or a broken bottle lying on dry grass can start a fire. Sometimes, though, a fire can start on its own. Wet hay (草) can begin burning by itself. This is how it happens: the hay starts to rot (腐烂) and begins to give off heat which is trapped inside it. Finally, it bursts into flames. That’s why farmers cut and store (贮存) their hay when it’s dry.
Fires have destroyed whole cities. In the 17th century, a small fire which began in a baker’s shop burnt down nearly every building in London. Moscow was set on fire during the war against Napoleon. This fire continued burning for seven days. And, of course, in 64 A.D. a fire burnt Rome. Even today, in spite of modern fire-fighting methods, fire causes millions of pounds’ worthy of damage each year both in our cities and in the countryside. It has been wisely said that fire is a good servant but a bad master .
39. The writer considers it ________ to sit beside a fire on a cold winter night .
A. nice B. dangerous C. unhappy D. painful
40. Which of the following describes the way how hay begins burning on its own ?
A. wet hay ---- becomes dry ---- gives off heat ---- burns
B. dry hay ---- gets too much heat from the sun ---- gives out heat --- starts to burn
C. wet hay ---- begins to rot ---- gives out heat ---- starts to burn
D. dry hay ---- gives off heat ---- starts to rot ---- starts to burn
41. Many big fires are caused __________ .
A. by cigarette B. by their own
C. by dry grass D. by people’s carelessness
42. How many examples did the writer give to show fires can destroy the whole city ?
A. One B. Two C. Three D. Four
43. Which of the following statement is not true ?
A. Fires still cause much damage now although there are modern fire - fighting methods .
B. Fires cause less damage in the country than in the city .
C. Fire can be man’s good friend and also great enemy .
D. One should be careful not to throw a lighted cigarette everywhere .
倍
…………2分从右出口人恰能脱离危险时有：
…………2分
，即人离左出口60m， …………2分
，即人的最小速度是火车速度的