构件按最小配筋率时，按代换前后（）相等的原则进行钢筋代换。A_爱下问搜题

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问题单项选择题

构件按最小配筋率时，按代换前后（）相等的原则进行钢筋代换。

A、面积

B、强度

C、刚度

D、变形

答案

参考答案：A

单项选择题

第1篇 Road Trip Vacations

It’s summer. In the United States, it’s the season of swimming pools, barbeques, camping and road trips.
Road trip vacations where the car journey is part of the fun are especially popular with college students, who like to explore the country on wheels. These budget trips are ideal for students who often have plenty of free time but little money.
"Ever since I went to college, I’ve been traveling around a lot, exploring the country," said Austin Hawkins, a 19-year-old college student from New York. This summer, Hawkins and his friends have spent weekends traveling in New England.
The best part about car trips, said Hawkins, is that you can be spontaneous. "On a road trip, if you get interested in things you see along the way you can stop and explore. "
Matt Roberts, a 20-year-old student from Ohio who drove to Montreal, Canada, agrees. "With road trips you don’t have to plan in advance, you can just get into a car and drive. "
Even with high gas prices, driving with friends is cheaper than flying. Roberts paid about 40 dollars for gas, but a round trip plane ticket would have cost nearly 400 dollars.
Driving trips first became popular in the 1920s. Newly paved roads and improved cars made it possible to travel longer distances. Motels started appearing outside cities.
By the 1950s, car ownership became the norm. Construction of the US interstate highway system began in 1956 and motel and restaurant chains popped up everywhere making long distance trips easier.
Today, the US has the highest car ownership rate in the world. Only 8 percent of American homes have no car, according to the most recent US census.
Though many college students don’t own a car, most have access to one. On many of Hawkins’ trips, they used a borrowed van.
Hawkins’ most memorable road trip took place over spring break. He and two friends drove from New York to New Orleans to volunteer, helping rebuild the city after Hurricane Katrina hit it last July. They crossed the country in two days and slept in their car in church parking lots.
Roberts’ road trip to Canada last winter was even more eventful. Upon arriving in Montreal, they were lost in a blizzard and shivering in the -25~cold. To find their hotel, they turned on a laptop and drove around in circles until they found a spot with wireless Internet coverage.
"I know we should have planned better, but we’re young. Now, when I see those guys I always say: ’Remember when we were lost in the snow storm! ’ I’ll never forget that. \

Which of the following statements is NOT true of American college students

A．They have little money.

B．They like traveling by bike.

C．They like to explore the country.

D．They often have plenty of tim

问答题

游离酸的测定中用氢氧化钠标准溶液滴至黄色变成蓝色，过了几分钟又变为黄色，这时你该不该再补滴定，使其变为蓝色？