下列关于氢气的叙述中，错误的是（ ） A．纯净的氢气在空气中安静地燃烧 B．氢气

阅读下面短文，简要回答所给问题。

It was near Christmas during my first semester teaching at a new school.I loved my small special class more than any group I had taught in the past.They were hungry for knowledge and I was enjoying teaching.

Other teachers had told me that our children were from poor families and not to expect any child to bring a Christmas gift.In fact，I wasn't expecting any gifts.

Imagine my surprise when every child brought me a gift on the day before our holiday break.First，I got a much­loved stuffed monkey from a shy girl.I was told，“He is my favorite，but I love you and I want him to be with you，Miss Taylor.”How thrilled I was!

Next came a new set of Christmas tree lights that was “missing” from a mother's cupboard.

Finally，I came to one little boy's gift which I had never received.It was an old，dirty and broken Christmas story book.Just when I wanted to express my happiness，I was interrupted(打断)by the giver，“And see，it is new！It still has the price tag.”

When other children laughed at him，I stopped them and said，“Oh，books are good in that way.The story is always new if you have not read it before.Now，let's share one together.”Everyone listened quietly as I read the most wonderful Christmas story of my life.

I still keep those Christmas gifts.They always remind me of my lovely kids.

小题1:Why did the teacher like her small special class?

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小题2:When did the children bring their teacher gifts?

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小题3:Who sent a stuffed monkey to the teacher?

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小题4:Was the Christmas story book new?

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小题5:How did the teacher feel when she got the gifts?

下列不属于农产品需求的特殊性的是（）。

A.农产品需求的派生性

B.需求价格弹性大于1

C.农产品需求具有多样性

D.同种农产品在不同销售阶段需求价格弹性不同

细菌L型是缺少了下列哪种成分（）

A.细胞膜

B.细胞壁

C.细胞质

D.异染颗粒

E.荚膜

司法警察业务技能训练，“劈击”动作主要用于（）。

A.戳对方面、喉、腹部

B.劈对方头、肩、颈、臂部

C.撩对方裆、腹、肋部

D.斩对方颈部

在建筑给水系统中，一般采用体积小、结构简单、效率高的（）。

A.轴流泵

B.混流泵

C.离心泵

D.真空泵