题干

在平面直角坐标系中,⊙P的圆心是(2,a)(a>2),半径为2,函数y=x的图象被OP所截的弦AB的长为23,则a的值是(    )

A:23   

B:2+2 

C:2 3

D:2+3

上一题 下一题 0.0难度 选择题 更新时间:2019-06-11 04:55:54

答案(点此获取答案解析)

B

同类题2

The man had died when the rescuers found her after the terrible earthquake. She was covered by a destroyed house. Through gaps (缝隙) of those ruins,the rescuers could see her last posture (姿势).It was something like an ancient person who was kowtowing (叩头),but it just looked strange because she was out of shape by pressure.

The rescuers confirmed her death by touching her through the gaps of the ruins. They shouted at the ruins again and again,knocked the bricks using various tools,but no reply inside.

Then the rescuing team went to the next building. Suddenly the leader ran back,calling“Come here.” He came to the body,put his hands under the woman,feeling and touching,then shouted loudly and gladly,“There is someone,a baby,still living.”

T hrough some efforts,re scuers cleaned up the ruins which blocked her. Under her body lay her baby,who was covered by a small red quilt(棉被).He was about 3 or 4 months’ old. Since well protected by his mother’s body,he was safe. He was in a deep sleep when the rescuer carried him out,and his lovely and peaceful face warmed everyone around him. The doctor,along with the rescuing team,took the baby out of the quilt to check if the baby was all right,and he found there was a mobile phone in the quilt. The doctor looked at the screen;a written me ssage was already there:“My dear baby,if you could live,don’t forget how much I love you. ”As a doctor,he experienced much of this type of separation;but at this moment,he cri ed. The mobile phone was passed,and every person who saw this message shed (流出)tears.

同类题4

读课文《走马灯的奥秘》选段,回答问题。

  茅(máo)以升七岁那年,过元宵(xiāo)节的时候,家里买了两盏(zhǎn)棱(léngɡ)柱形的走马灯。一盏挂在墙壁上,一盏悬(xuán)在堂屋中央。

  走马灯像磁(cí)石一样,把茅以升吸引住了。他仰着头,目不转(zhuǎn)睛地盯着走马灯。只见走马灯中间有一个轴(zhóu),轴上有一个可以旋(xuán)转的小轮子,轴心插着红蜡烛(làzhú),轮子四周插着彩色的小纸人和小纸马。蜡烛点燃以后,轮子就旋转起来,轮子四周的小纸人和小纸马也跟着转zhuàn动。明亮的烛光把小纸人和小纸马的影子投在灯壁上,十分有趣。

  他越看越入迷。一连串(chuàn)的问题,争着往他脑子里挤:小纸人、小纸马怎么会转?怎么有时转得快,有时转得慢呢?……

  他带着这些问题去问大人。大人告诉他:“是蜡烛的热气熏(xūn)的。”他听了大人的话,就把挂在墙上的走马灯取下来,“噗(pū)”的一声,把蜡烛吹灭了。小纸人、小纸马越跑越慢,最后停了下来。

  “那么,怎样才能让小纸人、小纸马跑得快一些呢?”他又提出了一个新问题。大人告诉他:“热气大,小纸人、小纸马就跑得快。”于是,他又拿来一支蜡烛,把两支一齐点燃。果然,小纸人、小纸马飞快地转起来……

这天晚上,茅以升特别高兴。虽然他没有完全弄明白走马灯转动的科学道理,但科学的种子已经播进他幼(yòu)小的心灵。“我”是采取什么招数来赢得棋局的胜利的?请在课文中找出相关的语句。