在探究定滑轮和动滑轮的省力特点时,某同学做出如图所示实验. (1)在甲图中,该

题型:问答题

问题:

在探究定滑轮和动滑轮的省力特点时,某同学做出如图所示实验.

(1)在甲图中,该同学分别用力F1、F2、F3使物体匀速上升,则F1、F2、F3的大小关系是______.

(2)在乙图中,该同学也分别用力F1、F2、F3使物体匀速上升,则F1、F2、F3的大小关系是______.

考点:定滑轮及其工作特点动滑轮及其工作特点
题型:问答题

Miss Williams is a teacher, and there are thirty children in her class. They are nice children, and Miss Williams like them all, but they often lose (丢失)some of the clothes. It’s winter, and the weather is very cold. The children’s mothers always take them to school with warm coats and hats and gloves(手套). The children come into the classroom in the morning and take off their coats and hats and gloves, and put the gloves in the pockets of their coats.

Last Tuesday, Miss Williams found two small blue gloves on the floor in the evening, and the next morning, she asked the children, “Whose gloves are these?” But no one answered. “Haven’t you got blue gloves, Dick?” she asked him.

“Yes, Miss Williams,” he answered, “but those can’t be mine. I’ve lost already.”

小题1:In winter, the children wore (穿) coats and gloves to _____.

A.play with snow

B.keep warm

C.play basketball

D.play outside小题2: The two small gloves were for _____.

A.Dick

B.other children

C.nobody

D.Williams小题3:Miss Williams found the gloves _____.

A.in the chair

B.on the floor

C.on the road

D.on the desk小题4: Which sentence is NOT right?

A.The children’s mothers often take them to school.

B.Children put the gloves in the pockets of their coats.

C.Dick hasn’t got any gloves.

D.Miss Williams thinks the children are nice.

题型:问答题

用所给的动词的正确形式填空。

     Tom 1             (be) a boy. He 2             (be) twelve years old. On Sundays, he doesn't 3             (go) to

school. In the morning, he 4             (do) his homework. In the afternoon, he 5             (play) with his friends.

In the evening, he 6             (watch) TV or 7             (read) some books. He 8             (like) Sundays.

题型:问答题

81,63,45,27,( )

A.7

B.15

C.9

D.11

题型:问答题

用清洗剂时不得用棉布在待胶接面反复擦拭,棉布每擦一次换一面,以免造成()。

A、重复污染

B、清洗不彻底

C、清洗剂浪费

D、棉布浪费

题型:问答题

下列()的密度与钻石的密度接近。

A.立方氧化锆

B.钇铝榴石

C.钛酸锶

D.碳硅石

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