学进去

在中，，点是边上两点，且垂直平分平分，则的长为（       ）

A．

B．

C．

D．

如图1，△ABC是边长为8的等边三角形，AD⊥BC下点D，DE⊥AB于点E
（1）求证：AE＝3EB；
（2）若点F是AD的中点，点P是BC边上的动点，连接PE，PF，如图2所示，求PE+PF的最小值及此时BP的长；
（3）在（2）的条件下，连接EF，若AD＝，当PE+PF取最小值时，△PEF的面积是　 　．

涟水外卖市场竞争激烈，美团、饿了么等公司订单大量增加，某公司负责招聘外卖送餐员，具体方案如下：每月不超出750单，每单收入4元；超出750单的部分每单收入m元．
   
（1）若某“外卖小哥”某月送了500单，收入　 　元；
（2）若“外卖小哥”每月收入为y（元），每月送单量为x单，y与x之间的关系如图所示，求y与x之间的函数关系式；
（3）若“外卖小哥”甲和乙在某个月内共送单1200单，且甲送单量低于乙送单量，共收入5000元，问：甲、乙送单量各是多少？

对于两个不相等的实数a、b，我们规定符号Min{a，b}表示a、b中的较小的值，如Min{2，4}＝2，按照这个规定，方程Min{，}＝－1的解为（     ）

A．1

B．2

C．1或2

D．1或－2

在平面直角坐标系中，关于的二次函数（，，为常数且）与轴交于两个不同的点，，与轴交于点，抛物线的顶点为．
   
(1)如图1，已知，，．
①求此二次函数图象的顶点的坐标；
②点是轴正半轴上的一个动点，过点作直线轴，交抛物线于点，交直线于点．当点在线段上运动时（不与点，重合），恰有线段，求此时点的坐标．
(2)如图2，当时，点是抛物线对称轴左侧图像上任意一点，过点作轴于点，连接交轴于点，连接、．则、有怎样的位置关系说明理由．

已知，在扇形中，，，点P在半径上，连接．

(1)把沿翻折，点O的对称点为点Q．
①如图1，当点Q刚好落在弧上，求弧的长；
②如图2，点Q落在扇形内部，的延长线与弧交于点C，过点Q作，垂足为H，，求的长；
(2)如图3，记扇形在直线上方的部分为图形W，把图形W沿着翻折，点B的对称点为点E，弧所在的圆与的延长线交于点F，若，求的长．

在中，且，点E是上一动点，连接，过点E作的垂线，交边于点F，则的最大值为_______．
   

以的顶点O为端点引射线OC，使∶=5∶4，若，则的度数是__________．

用方框中所给词组的适当形式填空，使得句子通顺，每个词组限用一次。有两个多余。

come around; tell...about; in fact; not...any more; work as; make a noise; chef’s special; in the end; hardly ever; worry about; all the time; deal with

1．On Harry Potter’s 11th birthday, Hagrid ________ to say “happy birthday” to him, and brings a really nice birthday cake.
2．This stewed lamb with carrots is ________. That’s why many customers would like to have the dish.
3．In Quick Change, Helen’s adoptive parents both ________ taxi drivers. They live in a flat. A taxi office is below their flat.
4．Please don’t ________ in the classroom when others are quietly reading or doing homework.
5．My grandpa doesn’t wear glasses ________. He only wears them when he’s reading.
6．We are foreign language learners and it is our job to ________ the world ________ China and China’s stories.
7．On a cold snowy day, Roger’s family are waiting for the newborn dogs. One little dog is almost dead. Roger tries to save him. ________, they get fifteen puppies.
8．In A little Trouble in California, the man that Andy and Mary meet on the beach looks dirty and unfriendly. ________, he is a police officer.
9．In a survey about family life, we find that mothers often ________ their kids a lot. Do their kids eat and sleep well? Do they have a good time in the school?
10．Mrs Green is afraid of dogs but her neighbor keeps two huge dogs in the yard. Her teenage son talks to the neighbor and helps her ________ the problem.

In the holiday, people use lanterns (灯笼) and lights to b________ the dark street. If you go to the center of the city, it is even like day time.