6 . Be cautious of Friday the 13^th！Many people think the day is unlucky.    1    （fortune）, there's only one Friday the 13^th this year. As the legend goes，you should try not     2    （break）any mirrors，walk under a ladder，or even spill any salt. Why？Researchers say    3     is tough to find out how the tradition came into being. Many believe it has     4    （religion）origins. In the Christian faith，there were 13 guests at table for the Last Supper，which was held the day before the Friday    5    Jesus died. Now，Friday the 13h has become a cultural wonder. Many Americans avoid the number 13 all together，    6    （include）hotel rooms and airplane seat assignments. It even costs couples less to get married on the day. There are many other    7    （explain）behind the luckless day. Simon Bronner，a professor of American studies at Pennsylvania State. University，    8    （believe）Friday the 13h is a way for people to pin their bad luck to a certain cause:. The fact should be    9    there's nothing special about the number itself. After all，the number 13     10    （consider）to be lucky in some countries，like Italy

last Thursday,   there was a   big fire in a big shop in our city. At 8:16 that morning,    1     the employees were working   busily in the 4-storeyed building, heavy smoke was seen     2     (come) out of the windows on the second floor. The fire lasted nearly an hour, and the majority of the 345 employees managed     3     (escape) from the fire. Unfortunately, 7were killed, and 23 injured, lightly or seriously.

Some workers     4     (complain) that aids came too late,     5     the firemen did come just 10 minutes after the fire was reported. To rescue everyone from the burning and smoking building in such a short time was too difficult. The only two exits of the big building were not enough for so many people to withdraw in    6    hurry.

The reason of the fire, according to an investigator, was       7     someone broke the non-smoking rule in the factory, because some cigarette   ends     8       (find). Next two weeks, 15 inspection teams will be working in all the factories     9     turn, aiming to clear away the possibility of more fires.     10    (hope), no disasters like this will happen again.

During the     1     (twenty) century , the temperature of the earth     2     (rise) about one degree Fahrenheit. It is a rapid increase when compared    3     other natural changes .

There is no doubt    4    the earth is becoming warmer. Scientists believe     5     is human activity that has caused this global warming. The increase in the earth's temperature is due to the    6     (burn) of fossil fuels. Some byproducts of this process     7     (call) “greenhouse” gases, the most important one of    8    is carbon dioxide. Without the “greenhouse effect”, the earth would be thirty-three degree Celsius    9     (cool) than it is. So, we need those gases. The problem begins when we add huge quantities of extra carbon dioxide into the atmosphere, causing the global temperature     10     (go) up.