题干

如图,在Rt△ABC中,∠B=90°,BC=5 3 ,∠C=30°.点D从点C出发沿CA方向以每秒2个单位长的速度向点A匀速运动,同时点E从点A出发沿AB方向以每秒1个单位长的速度向点B匀速运动,当其中一个点到达终点时,另一个点也随之停止运动.设点D、E运动的时间是t秒(t>0).过点D作DF⊥BC于点F,连接DE、EF.

上一题 下一题 0.0难度 选择题 更新时间:2019-02-07 09:08:47

答案(点此获取答案解析)

同类题2

阅读下列短文, 从每题所给的四个选项(A、B、C、D)中选出最佳选项。

    Do you enjoy reading? Here readers of your age from all over the United States recommend(推荐)great books for you to read:

①Don't Die, My Love  

  My favorite book is Don't Die My Love by Lurlene McDaniel.I love all her books.but this was the first one I read and I have to say, it is by far my favorite.It doesn't end like other books.

and I cried while reading.

②Nancy

    I think Nancy Drew is great! Nancy is a detective(侦探)who has many fantastic ideas! I love it because it's a book from when my grandma was my age, and I can share the fun with her !

③Skinny Bones

  I highly recommend Skinny bones by Barbara Park.It is funny, so please add it on your book list.You don't want to miss out funny stories !

 ④    ? 

    I would suggest             by Judy Blume.It is based on(基于)real things that happened to Judy Blume.It is about a girl, Alice, who meets some girls at a new state.They become friends, make a club and meet twice a week.They stop after two weeks because they all like a boy in their class and put him as Number One.I think every girl should read this because it is about our growing up.

⑥Neela:Victory Song

  I read a book called Neela:Victory Song and it was so good that I read it twice! It takes place in India in l936 and this l2-year-old girl named Neela tries to save her father! It has lots of his to “cal stories in it! I also learned a lot about different cultures! The writer's name is Chitra Banerjee Divakaruni.

同类题3

阅读下面短文,从各题所给的A、B、C、D四个选项中选出最佳选项。

D

    It happens every night—bedtime. But what if you're not sleepy? Should you still go to bed if you are just going to lie there with your eyes wide open? It's a problem that has been around as long as there are people trying to sleep.

    You might be excited by something you did in the day. You might be nervous about what you're going to do the next day. Maybe you don't like sleeping alone in your room. Maybe you have frightening dreams. All of these are possible reasons for your sleeping problem. However, there are some steps you can take to help you solve it.

    One thing that can help is talking to a parent or another trusted adult about what you're worrying about at bedtime. For example, if you're nervous about taking a test, or upset about being teased (被嘲弄) at school, it can really help to tell somebody. Knowing that somebody has heard you can help ease your mind so that you can have a good rest.

    Sleeping in a comfortable bed in a quiet and cool room is a good choice. If there's anything in your room that makes you feel uneasy or anxious at night, like a picture that looks strange in the dark, or a noisy faucet (水龙头) in the bathroom, be sure to ask your parents to move or fix it. Make sure electronics, such as mobile phones or iPads, are kept away from your bed. They can keep you excited, making it harder for you to fall asleep.

    If you are usually restless around bedtime, doing certain things to relax beforehand may help you fall asleep. Try to take more time to wind down by taking a warm bath, or listening to a bedtime story at least 30 minutes before you go to sleep. It also helps to follow a bedtime routine and go to sleep at the same time every night. As a result, your body will get the message that it's almost time to sleep. Your body will know to start feeling tired.

    In order to find the right solution for you, it's possible that you understand what exactly is keeping you up at night. Getting a good night's sleep is worth the time and effort of finding the right solution to your sleeping problem.

同类题4

阅读《陈涉世家》一文的节选文字,回答后面小题。
       陈胜者,阳城人也,字涉。吴广者,阳夏人也,字叔。陈涉少时,尝与人佣耕,辍耕之垄上,怅恨久之,曰:“苟富贵,无相忘。”佣者笑而应曰:“若为佣耕,何富贵也?”陈涉太息曰:“嗟乎!燕雀安知鸿鹄之志哉!”
       二世元年七月,发闾左谪(需改为走之旁)戍渔阳,九百人屯大泽乡。陈胜、吴广皆次当行,为屯长。天大雨,道不通,度已失期。失期,法皆斩。陈胜、吴广乃谋曰:“今亡亦死,举大计亦死;死,死国可乎?”陈胜曰:“天下苦秦久矣。吾闻二世少子也,不当立,当立者乃公子扶苏。扶苏以谏故,上使外将兵。今或闻无罪,二世杀之。百姓多闻其贤,未知其死也。项燕为楚将,数有功,爱士卒,楚人怜之。或以为死,或以为亡。今诚以吾众诈自称公子扶苏、项燕,为天下唱,宜多应者。”吴广以为然。乃行卜。卜者知其指意,曰:“足下事皆成,有功。然足下卜之鬼乎?”陈胜、吴广喜,念鬼,曰:“此教我先威众耳。”乃丹书帛曰“陈胜王”,置人所罾鱼腹中。卒买鱼烹食,得鱼腹中书,固以怪之矣。又间令吴广之次所旁丛祠中,夜篝火,狐鸣呼曰:“大楚兴,陈胜”。卒皆夜惊恐。旦日,卒中往往语,皆指目陈胜。