某蔬菜基地种植西红柿,由历年市场行情得知,从二月一日起的300天内,西红柿场售价与上市时间的关系如图一的一条折线表示;西红柿的种植成本与上市时间的关系如图二的抛物线段表示.
(1)写出图一表示的市场售价与时间的函数关系式p=f(t);写出图二表示的种植成本与时间的函数关系式Q=g(t);
(2)认定市场售价减去种植成本为纯收益,问何时上市的西红柿纯收益最大?(注:市场售价各种植成本的单位:元/102㎏,时间单位:天)
解:(1)由图一可得市场售价与时间的函数关系为f(t)=300-t,0≤t≤2002
如图,小佳通过实验测得L1、L2两只小灯泡电压的大小以及电源电压的大小,请你帮助小佳得出实验结论:并联电路中各支路两端电压 ____,并且 ____电源电压.
Do you have a room? I have a room. It is very beautiful. I clean it everyday. This is my room. It is not very big. There is a picture on the wall. There are some books on the desk. The dog is on the floor, and it is sleeping. Where is my sister? Oh, she is under the desk.
根据课文将正确的答案写在横线上。