11.  "She must be this year's Queen B!

12.  She must know how beautiful she was, since she kept looking into the mirror, appreciating herself from different angles.

13.  I must put all my efforts in study and there isn't much free time for me to participate the activities-- " Lily said gloomily. "

14.  She must be a student majoring in history, I was pretty sure.

15.  The other is that it is taken for granted that one must take part in the Students' Union.

16.  Most people believe that students of my campus must be very diligent in that we study in Nanjing University which is one of the most famous colleges in China.

17.  From the school bag he took with him, I could tell that he must be a science student-diligent.

18.  "Your work in physics must be very heavy, right? "

19.  "She must be a science girl!

20.  She must put her hand up immediately after the question is given and can always show the right answer to her class, like Hermione in Harry Potter.