Man’s understanding of nature is developing          . It never stays at the same level.

A. at the right time     B. for the first time       C. from time to time    D. all the time

Man’s understanding of nature is developing          . It never stays at the same level.

A. at the right time          B. for the first time       

C. from time to time       D. all the time

Man began to make use of fire long long ago. Fire is useful in many ways, but sometimes it is dangerous. If you are not (1)        with it, it can burn things or (2)       hurt you. A big fire can (3)        forests and tall buildings. Sometimes a piece of (4)        paper can cause a big fire. So please remember (5) ______      in the dry places like woods and forests (6)        throw a cigarette end on the grass and it’s also important for you to put the candles in the 7)       place. When you use candles at home ,you should (8)        your long hair away from the fire.
But if there is a (9)        in our building, what should we do with it? Pour some water (10)       your clothes. What’s more, put a (11)        towel (毛巾) over your mouth and your nose to keep the (12)______                out. You’d better run away from the fire as (13)        as you can. But you mustn’t rush! Or you may fall over and hurt yourself or others. Of course you should also call 119. On the phone you should clearly tell the firemen (14)      the fire is to help them get there without difficulty. By the way, Do not (15)        out of the window. Jumping may be more dangerous than the fire.
Keep ourselves away from fire and safety is above all!