题目

某四冲程汽油机工作时转速是2400r／min。关于此热机的工作下列说法正确的是A．压缩冲程中内能转化为机械能B．四个冲程中曲轴转动2圈，同时做功2次C．此汽油机每秒对外做功10次D．此汽油机每秒对外做功20次 答案：【答案】D【解析】试题分析：汽油机转速2400r/min，则每秒转40转，四冲程汽油机完成20个循环过程，在一个循环中对外做功一次，因此对外做功20次，正确的选D。阅读理解    Send us your joke, anecdote or story, and if we publish it in the magazine, we'll pay as follows:My Story $ 500    Personal stories beyond the call of daily life. They must be unpublished, original and less than 1,000 words.  Click here to read more stories.Kindness of Strangers up to $ 250    True accounts of good karma,__inspiring acts for unexpected kindness and generosity, or just something someone did that made your day different or changed your life. 100-500 words. Click here to read more stories.    Anecdotes and Jokes $ 50-$ 250    Funny things can happen at work and at home, especially when kids are around to pass comment. We may run your writing in Life's Like That, All in a Day's Work or As Kids See It, or as a short filler. Got a new joke? Send it in for Laughter, the Best Medicine. Click here to read more jokes.Send Us Your Punchline (妙语)    So you think of yourself as a bit of a jokester? See if you can come up with punchline to this month's joke...    You Said It    If you'd like to comment on something you saw in Reader's Digest magazine or on this website, this is the place to do it!    Is It Just Me    Can you be humorous about the trials and mysteries of modern life? Get it off your chest in 500 words. Click here to read more stories.1. This passage is written to ________.A. offer some wonderful stories to readersB. encourage people to write somethingC. show that making money is not difficultD. remind people that life is full of joy2. The underlined word "karma" is closest in meaning to ________.A. wish            B. explanationC. luck            D. imagination3. Which of the following statements is TRUE according to the passage?A. The magazine is mainly intended for entertainment.B. The more words you write, the more money you get.C. Anecdotes and Jokes isn't paid much attention to.D. New jokes can be sent in for Life's Like That.4. Where can you most probably see this passage?A. In a library.              B. In a magazine.C. In a story book.       D. On a website.