题干

如图,正方形纸片ABCD的边长为3,点E、F分别在边BC、CD上,将AB、AD分别沿AE、AF折叠,点B,D恰好都落在点G处,已知BE=1,则EF的长为(   )

A:1.5

B:2.5

C:2.25

D:3

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答案(点此获取答案解析)

B

同类题4

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    Each year,half a million people die from brain aneurysms(动脉瘤)—when a blood vessel bursts in the brain.An aneurysm is a bulge in a blood vessel that can burst.If that happens in the brain,it can be deadly.For survivors,physical disabilities are often severe.They may include memory problems,loss of balance,trouble speaking and even blindness.But new technologies are increasing survival rates and reducing disabilities.

    Beaumont Bacon is a survivor who makes light of her experience because she is a comedian.She uses humor to make others laugh.Now she's working on a new show.Michael Alexander is her doctor.He operated on Beaumont Bacon after her attack.“She had bleeding in the frontal area of her brain,so right above the eyes.The part that was in the brain was about maybe the size of an egg.So,that's a fairly large bleed.”

    Ms.Bacon had a better chance at survival than most people because of Dr.Alexander.He directs the Neurovascular Center in Los Angeles.The center offers new technologies that include placing a catheter(导管) into an aneurysm,then threading wires to promote blood clots(血栓).This technique reduces the chances of another burst blood vessel.“You don't have to open up the skull or open up the brain to do surgery.It's all done from inside the blood vessels.So it reduces the amount of blood loss,and the recovery is much faster.”

    For Beaumont Bacon's recovery,the hospital worked to prevent problems commonly found in patients with a burst aneurysm.The problems include brain swelling that can shut down blood vessels.She spent a month in a coma(昏迷)—unable to communicate with doctors,friends and loved ones.But with a year of treatment,she recovered.Now,she is making people laugh.

同类题5

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    I have two sons. They are as different as night and day. My youngest is sweet, loveable, easy-going, and finds joy in everything. My oldest we've nicknamed the “Evil Genius” is ambitious, self-confident, and suffers no fools. Whenever we mentioned Santa my husband and I were rewarded with major eye rolling and deep sighs from my oldest. At first we both tried to ignore it.

    We both knew that our eldest had figured out the big secret. But I'd be damned(指责) if he was going to ruin it for his six-year-old brother who had plenty of Santa-loving years ahead of him. I looked at my husband in the eye and said, “I'll handle this.” to which he responded “Okay just be careful because I'm not sure he knows - he might just be acting like it.” But I knew. And I had it in my mind that he was about to break his younger brothers spirit and break the news to him. I was afraid he was going to take the Christmas spirit away from my sweet innocent youngest and stamp all over it. I had to protect him. I needed to control this now before it got out of control. I rushed into the play room where my oldest was playing alone. I looked him dead in the eyes and said: “Well you know Santa isn't real, right?” And as I stared at my eight-year-old son for what seemed like a long time of silence, his eyes started to fill with tears. And a tear dropped down his cheek when he screamed out, “He's not?” “Um well it's not that he's not real (shut up you idiot- stop saying he's not real), but he doesn't really make and deliver all the toys. Dad and I get some of them for you. So he's real. He's just got a little help from us.”

    The Evil Genius wasn't buying it. He just sat there looking at me with an expression of doubt. You know when you make a terrible mistake but you can't stop yourself from making it worse? That was me because I just had to know. I had to know why he had seemed to be over Santa. So I asked him why he rolled his eyes and sighed every time his father and I mentioned Santa, to which he replied that kids at school had been saying Santa wasn't real but that he still thought he was.