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Exercise 6 Fill in the blanks with the words or expressions given. Change the form if necessary. leisure policy pretend identity favourite detail protect deserve related to when it comes to trick into on one’s guard give out insist on in person Be ____________ if you get a phone call from someone claiming to be from your bank asking for your personal details. When you meet someone ____________ or talk face-to-face you should be certain that the person you are communicating with is who they say they are. _____________ shopping online, most people go looking for one thing: the lowest price. Find something that you like to do for yourself; you ____________ to have some happiness and fun in your life. The danger is that they could ____________ to be you and take money out of your savings account. The company admitted it had failed to ____________ the worker from danger. To make sure your personal ____________ and your money remain safe, we have some tips for you. Keep safe by being careful not to ____________ your personal information to people online. Some people online may ____________ you ____________ giving out your personal financial information. I recently read an article that says Americans spend half their____________ time online. Our site brings you news, research, and other information ____________ the issue of staying online safe. Police are trying to discover the ____________ of a baby found by the side of a road. If you ____________ meeting an online friend take a friend (or two) with you and tell someone where you will be. If you already have a ____________ hotel, we can help you find out whether it has available rooms and rent one online.
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【单选题】设 S 1 =1+ 1 1 2 + 1 2 2 ， S2=1+ 1 2 2 + 1 3 2 ， S3=1+ 1 3 2 + 1 4 2 …， S n =1+ 1 n 2 + 1 (n+1) 2 ，设 S= S 1 + S 2 +…+ S n ，其中n为正整数，则用含n的代数式表示S为（ ）
A.
n 2 -n-1 n+1
B.
n 2 +2n n+1
C.
1 n(n+1)
D.
2n+1 n(n+1)
【单选题】设A={1,2,3}, R={,,,}, 则r(R), s(R), t(R)=_____.
A.
r(R)={<1,2>,<2,1>,<1,3>,<1,1>,<2,2>,<3,3>}, s(R)={<1,2>,<2,1>,<1,3>,<1,1>,<3,1>}, t(R)={<1,2>,<2,1>,<1,3>,<1,1>,<2,2>,<2,3>}
B.
r(R)={ <1,2>,<2,1>,<1,3>,<1,1>,<3,1>}, s(R)={<1,2>,<2,1>,<1,3>,<1,1>,<3,1>}, t(R)={<1,2>,<2,1>,<1,3>,<1,1>,<2,2>,<2,3>,<3,2>}
C.
r(R)={<1,2>,<2,1>,<1,3>,<1,1>,<2,2>,<3,3>}, s(R)={<1,2>,<2,1>,<1,3>,<1,1>}, t(R)={<1,2>,<2,1>,<1,3>,<1,1>,<2,2>}
D.
r(R)={<1,2>,<2,1>,<1,3>,<1,1>,<2,2>,<3,3>}, s(R)={<1,2>,<2,1>,<1,3>,<1,1>,<3,1>}, t(R)={<1,2>,<2,1>,<1,3>,<1,1>,<2,2>,<2,3>, <3,2>}
【单选题】设向量α=α1+α2+…+αs(s>1)，而β1=α-α1，β2=α-α2，…，βs=α-αs，则( )．
A.
r(α1，α2，…，αs)=r(β1，β2，…，βs)
B.
r(α1，α2，…，αs)>r(β1，β2，…，βs)
C.
r(α1，α2，…，αs)1，β2，…，βs)
D.
不能确定两者之间的大小关系
【多选题】下列关于丽江古城的说法中,正确的有
A.
丽江古城是世界文化遗产
B.
丽江古城没有城墙
C.
丽江古城的建筑体现纳西族的艺术风格
D.
丽江古城是中国保存最完整的明初县治砖城
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