港珠澳大桥是迄今世界最长的跨海大桥 ,如图所示 ,总长55公里 ,两 边有长长的引桥,其中海中隧道 6.7公里(40米深 )。建造隧道时 ,将沉管两端密封 ,如同一个巨大的长方体空心箱子,然后让其漂浮在海面上,排水量为75000吨 ,再用船将密封沉管拖到预定海面上,向其内部灌水使之沉入海底在 ⒛18年央视春晚上，由百度Apollo无人车组成的百余车辆 ,成 为首批跑上港珠澳大桥的车队，在无人驾驶模式下完成“8”字交叉跑等动作，300架无人机跃过港珠澳大桥上空 ,近百艘无人艇穿过大桥。

下面是3个氨基酸的结构式，由这3个氨基酸按顺序脱水缩合所形成的化合物中，含有的氨基、羧基和肽键的数目依次是

    During my second year of nursing school，our teacher gave us a test.I was a hard﹣working student and I did well1all the subjects.I finished the questions 2until I read the last one，"What is the first name of  the woman3cleans the school？"

    Of course this was only a joke.I saw4 cleaning woman every day.She is short and about 60 years old.

    She has dark hair.5 how would I know her name？I have never talked with her before.In fact，I've never even thought about6to her!I stared at my paper.7 guilty I felt! Finally，I handed in my paper，but the last question 8.

    Before the class ended，one student asked the teacher9the last question would count into our grade.

    "Of course，"the teacher said，"In your life，you will meet10 people.It's important for you 11 them.They deserve（值得）your attention and care，even if all you do is just 12 hello."I'll never forget that lesson.Everyone deserves our attention and we13 try to get to know all the people who work and live around us.That was14 lesson of my life.Later that day，I 15that the cleaning woman's name was Dorothy.