论述完全竞争市场长期均衡的实现过程和特点。
案例:在学习了“基本不等式”后,教师要求学生解决如下问题:设x、y均为正数,且满足x+2y=1,求1/x+1/y的最小值。
一位学生给出的解法如下:

问题:
(1)指出上述解答的错误之处,分析错误原因,并给出正确解法;
(2)简述求二元函数最值的一般解法有哪些。
设计任务:请阅读下面学生信息和语言素材,设计20分钟的英语听说教学方案。教案没有固定格式,但须包含下列要点:
● teachingobjectives
● teachingcontents
● key anddifficult points
● major stepsand time allocation
● activitiesand justifications
教学时间:20分钟
学生概况:某城镇普通中学初中一年级第二学期学生,班级人数40人。多数学生已经达到《义务教育英语课程标准(2011年版)》二级水平。学生课堂参与积极性一般。
语言素材:
Conversation 1
Tom: Hey,Peter.
Peter: Hi.Tom.
Tom: How's the weather down there in Shanghai?
Peter: it's cloudy. How's the weather in Moscow?
Tom: It's snowing right now.
Conversation2
Peter: Hi Aunt Sally.
Aunt 8ally: Hello,Peter.
Peter: How's the'weather in Boston?
Aunt Sally: Oh, it's windy.
Conversation 3
Peter: So, how's the weather in Beijing?
Julie:It's sunny.
Conversation 4
Peter: Hi,Uncle Bill.
Uncle Bill: Hello, Peter.
Peter: How's the weather in Toronto?
UncleBill: It's raining, as usual!