如图所示,V1和V2是完全相同的两个电压表,都有3 V和15 V两个量程,闭合开关后,发现两个电压表偏转的角度相同,则( )
A:R1∶R2=1∶4
B:R1∶R2=4∶1
C:R1∶R2=1∶5
D:R1∶R2=5∶1
将左边和右边的句子连成对话。
①Six oranges, please.____ a. Good afternoon.
②Good afternoon.____ b. Thank you.
③How much are they?____ c. OK. Here you are.
④Good boy.____ d. An apple, please.
⑤Can I help you?____ e. Ten yuan, please.
阅读下面短文,从短文后所给的A、B、C、D四个选项中选出能填入相应空白处的最佳选项。
This is an apple tree. There are many 1 on the tree. There are some 2under it, too. They are 3 happily. Under the tree I can 4 a boy and a girl. They're playing games with the dogs. The boy is 5 a blue sweater and white shoes. He is Jim. He is 6 American student. He is 14. He 7 his school very much. The girl is Jim's sister, 8 name is Cindy. She is 11. She is in a yellow dress. Her shoes are yellow. 9 . Now they are standing here, they are waiting for their friends. They 10 to play games under the tree.
功率一定的拖拉机在深耕时的行驶速度比在公路上慢,这主要是为了( )