如图甲所示，电源电压恒定，导体电阻的阻值不随温度的变化而变化．某同学把不同的定值

This morning I went to a nearby food store to buy some breads. After the man in the store packing the bread in a small bag for me, I began to walk home with bag in my hand. On the way I met my next-door neighbor, Miss Wang, that was walking her dog .We greeted with each other and begin to talk about the weather. As we were talking, his dog came up at the bag in my hand though the bread gave off a delicious smell. As a result, some of the bread fell to the ground or the dog began to enjoy it. Five minutes late, I was back at the store to buy bread again.

标志着中国新民主主义革命开始的历史事件是[ ]

A．辛亥革命        

B．鸦片战争        

C．五四运动        

D．新文化运动

根据下列资料，回答第70~72题。 2009年度全国旅行社营业收入为1806.53亿元，同比增长8.64%；毛利润总额为134.36亿元，毛利率为7.44%；净利润总额为11.48亿元，净利率为0.64%。 2009年度全国旅行社的旅游业务营业收入为1745.59亿元，同比增长8.87%；旅游业务毛利润为120.27亿元，旅游业务毛利率6.89%；实缴税金为12.69亿元，同比增长12.37%；外汇结汇10.51亿美元，同比减少11.24%；全年促销费支出为6.76亿元，同比增长13.87%。

2008年度全国旅行社入境旅游业务营业收入约为多少亿元（）

A．185

B．210

C．225

D．235

道路的路面直接承受汽车荷载，抵抗车轮的磨耗。根据路面及路面面层结构的力学特性，路面分为柔性路面、刚性路面、半刚性路面三种类型。

线路设备状态评定，是考核线路设备管理工作和线路设备（）情况的基本指标。