19.   Our math teacher is really     (understand). We all like him very much.

18.   ―Who helped Eric make the model plane?
―Nobody. He made it by     (he).

17.   She was afraid     (walk) alone at night.

16.   My  cousin was  careless  and  he  made many    (mistake) in the exam.

15.   - Why did you t     him? Because he did lots of things for us.

14.   There are many things to do for the trip, but I think the first s     is to make a plan.

13.   ―How do you often s     your problems?

―I often ask my friends for help.

12.   Problems and worries are n     in life.

11.     There was no money in his w      ， so he didn't buy anything.

(   ) 10. Most of us thought Alice couldn't do the job well because she had little     .
A. temperature      B. experience C. difference      D. discussion