题干

某蛋白质由3条多肽链、N个氨基酸组成,下列关于该蛋白质说法正确的是(   ) 

A:形成该蛋白质时产生了N个水分子

B:该蛋白质中至少含有N个肽键

C:该蛋白质中至少含有3个游离的羧基

D:合成该蛋白质至少需要20种氨基酸

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C

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  Dear Peter,

    Without knowing more about you,it's hard for me to give you some good advice.

    But firstly.I am sure that you are 1 .You said that nobody would care if you left  home.What about your2  ? And other family members ?It seems that you are very 3.You'd better go to a doctor or talk  4 your parents.They will be able to help you.

    Secondly,I'm sure there's someone else in your class who feels lonely,  5.You never know 6other people feel.Try to make friends with your classmates.And you could  7  a club to meet new people and make friends,too.

    You 8  find happiness in yourself.So my 9advice is to write a list of all the good things about yourself,learn to like yourself,and then  10  will see your confidence(信心)and like you,too. 

                                                                                                                                                                                                                   Yours,

                                                                                                                                                                                                                     Lily