简易呼吸器的使用。

阅读理解。

     Did you know that tea, the most popular drink in the world, was invented by accident? Although tea

wasn't brought to the western world until 1610, this beverage (饮料) was discovered over three thousand years before that.   According to an ancient Chinese legend c传说), the emperor Shen Nong discovered

tea when he was boiling drinking water over an open fire.  Some leaves from a nearby bush fell into the

water and remained there for some time. The emperor noticed that the leaves in the water produced a

pleasant smell. Later he decided to taste the hot mixture. It was quite delicious.  And in this way, one of

the world's favorite drinks was invented.

根据短文内容，回答下列问题。

1.  When was tea invented?

___________________________

2.  Who was tea invented by?

___________________________

3.   How was it invented?

___________________________

4.  When was tea brought to the western world?

___________________________

5.What is the article about?

___________________________

（1）x²+4x+3=0

（2）（2x-1）²=25

（3）3x²-5x-2=0

（4）（2x+1）²=3（2x+1）

女性经期卫生要做到[ ]

A．心情舒畅、情绪稳定

B．注意外阴部的卫生

C．注意饮食、防寒和休息

D．以上都正确

一绝缘细绳的一端与可绕O点转动的轻质杠杆的E端相连，另一端绕过动滑轮D、定滑轮C，与滑动变阻器的滑片P相连；B为一可导电的轻质弹簧，如图所示接入电路中，一端通过绝缘绳固定在地面上，另一端与滑片P相连；一人站在地面上拉住与杠杆H端相连的细绳。已知电源电压为8V，灯泡标有“6V 3W”字样，人的质量为50kg，人与地面的接触面积为50cm²，EO:HO=2:5。人对绳子拉力最小时，电流表示数为I₁，且滑片刚好位于滑动变阻器的a端；人对绳子拉力最大时，电流表示数为I₂，且I₁:I₂=2:1，滑动变阻器的阻值与弹簧所受拉力的关系如下表所示：

不计杠杆、弹簧、滑片、细绳的重力，不计摩擦，不计弹簧电阻。整套装置始终处于平衡状态，物体A始终不离开地面。灯泡电阻不变，且不会被烧坏。g=10N/kg。求：

（1）人的拉力最大时，滑动变阻器接入电路的阻值是多少？

（2）物体A的质量是多少？

（3）人的拉力最大时，人对地面的压强是多少？

（4）当灯泡正常发光时，物体A对地面的压力是多少？

下列关于氮氧化物引起的损伤叙述错误的是（）

A.氮氧化物又俗称硝烟

B.水溶性不大，主要引起上呼吸道损伤

C.NO₂主要导致肺水肿

D.NO可导致高铁蛋白血症

E.NO可引起中枢神经系统损伤