问题
多项选择题
常用的液压基本回路按期功能可分为（）和顺序动作回路
A.拉力控制回路
B.方向控制回路
C.压力控制回路
D.速度控制回路
答案
参考答案：B, C, D
搜题请搜索小程序“爱下问搜题”
常用的液压基本回路按期功能可分为（）和顺序动作回路
A.拉力控制回路
B.方向控制回路
C.压力控制回路
D.速度控制回路
参考答案：B, C, D
When I was nine years old, I used to go to the post office with my mother, sending greeting cards to my aunt in Singapore. To me, these trips were really memories. And receiving mail through a mailbox outside our gate was just as exciting. My small hands could get the mail without using a key! I always could never to see how much I was getting. Oh, a letter! From Singapore! I would run back home and show it to my . When there was a letter for me, I wouldn’t run—I would open it right there. After my family moved back to Singapore, I going to the post office. Years later, my company sent me to Shanghai, and the post office found me again. Two years ago I celebrated my with five friends on top of the mountain in Longsheng, China. At sunrise we up to a beautiful view from the mountain top. Later in the afternoon, as we were going the mountain and returning from the sunrise viewing place, a small caught our attention. It only sold noodles, coffee and had a China sign. We asked the owner if she could really send mail. She happily said yes. It seemed hard to believe, we were at the highest top of the mountain. I picked one postcard out and asked my friends to write a birthday note. We bought a stamp, wrote some notes and gave the shop owner the postcard. Three weeks later, I arrived home and my mailbox: Hello, postcard! I broke into a big smile. That birthday postcard attracted me again to the post office and all its delights. I had the post office all these years. Today I send postcards to friends. And every time I am at the post office buying stamps, I cannot help but smile—how one postcard will make its way across the world and brighten up someone’s day.
|