在室温20℃下,比较两根镍铬合金丝电阻大小,下列说法正确的是( ) A.横截面积

题型:选择题

问题:

在室温20℃下,比较两根镍铬合金丝电阻大小,下列说法正确的是(  )

A.横截面积小的导线电阻比横截面积大的导线电阻小

B.长度较长的导线电阻比长度较短的导线电阻大

C.横截面积相等时,长度较长的导线电阻小

D.长度相同时,横截面积较小的导线电阻大

考点:影响电阻大小的因素
题型:选择题

物资储备定额的种类及其含义是什么?

题型:选择题

阅读理解.

     I'm Tony. My best friends are Frank and Cindy. We often do many things together. Frank lives

next to my home and we are in the same class. He is thirteen years old and tall and medium build. He

has curly hair and blue eyes. He's good-looking and very clever. He's good at math and often helps

me with my homework. He likes wearing black pants and yellow T-shirts.

     Cindy doesn't go to my school. She's eleven years old. She is thin and medium height. She has

curlyblonde hair and her eyes are brown. She is good-looking, too, but a little bit shy. She is good at

playing the guitar. Her favorite subject at school is music. She often teaches Frank and me to play the

guitar after class.

     The three of us have great fun together, and we help each other and sometimes play video games

at my house.

1. What things do the three children do together? They _____.

A. play baseball

B. play video games

C. play the guitar

D. both B & C

2. _____ eyes are blue.

A. Frank's

B. Cindy's

C. My

D. Tony's

3. _____ good at math.

A. Frank is

B. Cindy is

C. Iam

D. Tony is

4. _____ is good-looking, but a little bit shy.

A. Frank

B. Cindy

C. Tony

D. My friend

5. Where do they play video games? _____.

A. at school

B. at Frank's house

C. at Cindy's house

D. at Tony's house

题型:选择题

当PE管受外力损伤引起漏气时抢险队员到达现场后,应首先切断气源,根据管网实际情况,用()将漏气管线夹住,止住气源并用相应的管件将断管连接起来。

A、扳子

B、夹具

C、工具

D、钳子

题型:选择题

总碱度测定需要什么试剂和仪器?

题型:选择题

设计饲料配方时,应掌握使用适度的原料种类和数量,同时考虑动物废弃物等对人类生存环境的不利影响,这是遵循了全价饲料配方设计的()原则。

A、营养性

B、安全性

C、经济性

D、市场性

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