用括号内所给动词的适当形式填空，必要时可加助动词或情态动词。
Mr. Jones liked to be comfortable, so every time he took a train, he used to put a bag on the seat next to him and pretend that it belonged to a friend who had gone 小题1:(buy) something at the station.
One day, Mr Jones did this when the train 小题2:(be) very crowded. When nearly all the seats 小题3:(take), an old man got on (上) the train. Looking at the bag, he asked, “Is this seat taken?”
“Yes,” said Mr Jones, “It belongs to my friend who has gone to buy some cigarettes. He 小题4:(come) back soon.” Pretending to worry about his friend, he 小题5: (look) out of the window.
“All right,” said the old man, “I’ll just sit here until your friend 小题6: (return), if you don’t mind.” Mr Jones couldn’t say anything. Just then the train began 小题7:(move) out of the station.
“Well,” said the old man, “what a pity (遗憾)! Your friend 小题8:(miss) the train already, but his bag is still here.” Before Mr Jones could say anything, the old man took the bag and threw it out of the window. |
与时间
小时
间的关系为
．如果在前
个小时消除了
的污染物，试求：
个小时后还剩百分之几的污染物？
所需要的时间．（参考数据：
）
曲线
处的切线斜率
有三个互不相同的零点0，
，且
。若对任意的
，
恒成立，求m的取值范围。
