题干

aR ,函数 f(x)=ex+aex 的导函数是 f(x) ,且 f(x) 是奇函数,则a的值为(    )

A:1

B:- 12

C:12

D:-1

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答案(点此获取答案解析)

A

同类题1

阅读理解

    When Abraham Lincoln was young, he worked in a store. One day a woman came into the store and bought some things. They added up to two dollars and six and a quarter cents.

    The bill was paid, and the woman was satisfied. But the young storekeeper, not feeling quite sure about his calculations(计算), added up the things again. To his surprise, he found that it should have been but two dollars.

    “I've made her pay six and a quarter cents more,” said young Abe, upset.

    It was an unimportant thing, and many salespersons would forget it, but Abe was too careful for that.

    The money must be paid back, he decided.

    At night, he closed the store and walked to the home of his customer. He explained the matter, paid over the six and a quarter cents, and returned satisfied.

    Here is another story of young Lincoln's strict honesty. A woman entered the store and asked for half a pound of tea. The young man weighed it out. This was the last sale of the day.

    The next morning, when beginning his duties, Abe discovered a four-ounce weight on the scales(磅砰). It flashed upon him at once that he had used this in the sale last night, and so, of course, given his customer short weight. Many people would not have been much worried by this discovery. But Abe weighed out four ounces of the tea, shut up the store, and carried it to the customer. I think that the name, so often given in late times to President Lincoln, of “Honest Old Abe", was well deserved(应得的).

同类题5

阅读理解

     I was very disappointed not to be able to go to the jazz concert last Friday. The advertisement in the paper said that you could buy tickets at the theatre box in Richland Hills any day between 10:00 and 4:00. Since I work from 9:00 to 5:30, the only time I could go to the theatre was during my 45-minute lunch break.

    Unfortunately, the theatre is on theother side of the town, and the bus service between my office and Richland Hills is not very good. Butif you are lucky, you can make the round trip in 45 minutes. Last Monday, Istood at the bus stop for 15 minutes waiting for the bus, By the time I saw onecome around the corner, there was not enough time left to make the trip.

     So I gave up and went back to the office. The same thing happened on Tuesday, and again next day. On Thursday, my luck changed. I got on a bus right away and arrived at the theatre in exactly 20 minutes. When I got there, however, I found along line of people at the box office, I heard one man say he had been waitingin line for over an hour. Realizing I would not have enough timeto wait in line. I caught the next bus and headed back across the town.

    By Friday I realized my only hope was tomake the trip by taxi, it was expensive, but I felt it would be worth it tohear the concert. The trip by taxi only took 10 minutes, but felt like an hour to me. When I got to the theatre, I was relieved to see that nobody was waiting in line. The reason, however, I quickly discovered, was that they had already sold all the tickets.