完形填空。先通读下面的短文，掌握其大意，然后在每小题所给的A、B、C、D四个选项中，选出可以填入空白处的最佳选项。 Thousands of years ago, people did not know 1 to make a fire. When it was very 2 at night, they could not sleep well. Sometimes lightning hit (打，击) a 3 and started a fire. At first people were both surprised and 4 to see the fire. They were afraid to go up. Later a few 5 men took some of this fire and made a fire near their homes. They used the fire to keep them warm and to cook food. When they had a fire, they did not let it 6 burning. If it stopped, they could not start it again. Maybe they had to 7 for a long time, sometimes for 8 . Later they 9 how to make a fire with pieces of wood. Now we have matches, we can put them in our pockets and make a fire when we want to make it. But we have to be 10 with fire. (     ) 1．A．what (     ) 2．A．cold (     ) 3．A．person (     ) 4．A．glad (     ) 5．A．very (     ) 6．A．stop (     ) 7．A．work (     ) 8．A．minutes (     ) 9．A．forgot (     ) 10．A．angry B．how B．hot B．mountain (山) B．afraid B．brave B．make B．play B．hours B．decided B．pleased C．when C．warm C．field C．ready C．sad C．be C．wait C．days C．learned C．careful D．where D．cool D．forest (森林) D．tired D．happy D．start D．1ive D．years D．told D．busy