题目

某市化工材料经销公司购进一种化工原料若干千克，价格为每千克30元．物价部门规定其销售单价不高于每千克60元，不低于每千克30元．经市场调查发现：日销售量y(千克)是销售单价x(元)的一次函数，且当x=60时，y=80；x=50时，y=100．在销售过程中，每天还要支付其他费用450元． （1） 求出y与x的函数关系式，并写出自变量龙的取值范围； （2） 求该公司销售该原料日获利W(元)与销售单价x(元)之间的函数关系式； （3） 当销售单价为多少 Title Time Event Grandmother Student today An  83—year—old great grandmother received a bachelor’s degree(学士学位) from South—Eastern University today, more than 50 years after she took her first college course. Early Spring Storm last night An early spring heavy snow dumped 18 inches of snow on the city in less than six hours last night. Two Men Win Freedom today Two men picked up for disorderly conduct(不法行为)won their freedom today when they helped police officers save 20 persons from burning North Side apartment building. Henley Street Bridge Closed  On Friday The Henley Street Bridge over the Tennessee will be closed at 8:00 on Friday, a State Highway official said today. Husband Kills Wife today Just 15 minutes after  he shot and killed his unfriendly wife , a 22-year –old truck driver jumped to his death from the State Street Bridge. 1.From the first piece of news we know that ______. A．it took the old woman over 50 years to study at South-Eastern University. B．the great grandmother was the oldest who received a bachelor’s degree. C．the 83-year-old woman’s story surprised everyone. D．the 83-year-old woman has a strong will. 2.The underlined word “dumped” means____. A．fell              B．left              C．hit               D．lasted 3.In the third piece of news, “picked up” means ______. A．given a ride        B．saved from danger   C．freed             D．caught 4.Which of the following is right according to the last piece of news? A．The wife was a 22-year-old truck driver. B．The wife was shot after her husband died. C．Shortly after having shot his wife, the young truck driver finished himself. D．The wife died, but the husband didn’t. 5.Which is TRUE according to the news above? A．A person who is about 70 years old can get a bachelor’s degree. B．It never snows heavily at night in spring. C．There were only 20 persons living in North Side apartment building. D．Maybe today is Wednesday.