下列字注音完全正确的一项是(   )

已知乳酸的结构简式为  ．试回答：

（1）乳酸分子中含有____ 和____ 两种官能团（写名称）；

（2）乳酸与金属钠溶液反应的化学方程式为____ ；

（3）乳酸与Na₂CO₃溶液反应的化学方程式为____ ；

（4）当乳酸和浓硫酸共热时，能产生多种酯类化合物，任意写出两种该类产物的结构简式

____ 　、____ ．

完形填空

  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

直线l的倾斜角为$\alpha$，且$\sin \alpha =\frac{3}{5}$，则直线l的斜率是(     )