按照题目要求作图 （1）如图是用螺丝刀撬开桶盖的示意图，请在图中画出动力F1的力

短文改错

Yesterday a school boy is daydreaming in class.Not knowing that he was doing, he put a pen cap

into his mouth.A few minutes late, he was terrified to find that he had swallowed it!The teacher was

shocking when the boy stood up and said, "I've just swallowed a pen cap."He was quickly sent the

nearest hospital.There a doctor examined his and said the best treatment was to take some medicines

so that the pen cap could pass natural.Three hours later the boy successfully made it."She is really lucky, " said the doctor."It's not rare that small children put things into their mouths for a fun.It's very danger."

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开口于蝶筛隐窝的鼻旁窦是（）。

A.筛窦后组

B.筛窦前、中组

C.上颌窦

D.额窦

E.蝶窦

下列比较中正确的是（　　）

A．离子的还原性：S^2-＞Cl^-＞Br^-＞I^-

B．氧化性：F₂＞Cl₂＞S

C．酸性：H₂SO₄＞HClO₄＞H₃PO₄

D．非金属性：F＞Cl＞S＞O

手三阳经与足三阳经交会处是（）

A.手

B.足

C.胸

D.腹

E.头