问题 选择题

如图所示,在高山滑雪中,质量为m的运动员静止在准备区的O点,准备区山坡倾角为θ,滑板与雪地间的动摩擦因数为μ,这时(  )

A.运动员受到的静摩擦力为μmgcosθ

B.山坡对运动员的作用力为mg

C.山坡对运动员的支持力为mg

D.山坡对运动员的摩擦力大于mgsinθ

答案

运动员的受力如图,

根据共点力平衡得,运动员所受的静摩擦力f=mgsinθ,山坡对运动员的支持力N=mgcosθ,

因为山坡对运动员的作用力是支持力和摩擦力的合力,与重力等值反向.故B正确,A、C、D错误.

故选B.

完形填空

第二节:完形填空(共20小题;每小题1分,满分20分)

阅读下面短文, 掌握其大意,从短文后各题所给的四个选项(A、B、C、D)中,选出最佳选项。并在答题纸上将该选项标号涂黑。

I lived in Dallas, Texas nearly all my life with my mom, dad and older sister. We were     21    to respect others, value education, and get all that we could out of life. My parents always say, “   22    hard and the world is yours.” They are never without a    23  word of advice or a bit of encouragement when life gets tough.

My parents always    24    me to go to college. However, when I     25    at 16 years old that I’d rather get married to a man than go to college, they    26    stopped telling me they loved me and I could do anything I wanted to.     27    , they persuaded me. I graduated from high school and currently     28     the University of Oklahoma studying medicine. I want to make the     29    a better place to live in.

Every time I call home to tell them about a     30    I received in Chemistry Lab or Microeconomics or     31     class it is that I’m working hardest for at the moment, they tell me how     32    of me they are. I know there are college kids out there that have no one to call home to when they get an “A” on a project and I feel incredibly     33    to have my parents.

Don’t get me wrong: We’ve had our share of     34   . I was the angry teenager and they were the awful    35     that wouldn’t let me stay out all night or let me get my tongue pierced. But somehow, we    36   to work through those issues. They never    37   loving in me or believing in me.

I    38   everything I am to my parents. Without their constant love and       39    , I wouldn’t believe I can change the world. My parents taught me to always          40    for what I believe in. So I’m working toward something really great and can only hope I continue to make them proud.

21. A. brought                     B. introduced         C. raised                       D. produced

22. A. Educate                     B. Work                C. Train                       D. Practise

23. A. helpful              B. harmful             C. stressful                   D. meaningful

24. A. reminded            B. expected          C. supposed                  D. designed

25. A. hesitated             B. judged                     C. fixed                        D. decided

26. A. never                  B. ever                  C. seldom                     D. hardly

27. A. Carefully            B. Hopefully          C. Thankfully               D. Delightfully

28. A. serve                  B. attend               C. admit                       D. join

29. A. fortune               B. planet               C. universe                   D. world

30. A. grade                  B. problem            C. failure                      D. value

31. A. whenever            B. wherever           C. whichever                D. however

32. A. modest               B. proud                  C. ashamed                   D. nervous

33. A. annoyed                 B. praised              C. relaxed                     D. blessed

34. A. lessons                B. problems           C. moments                  D. experiences

35. A. teachers                     B. directors            C. couples                    D. parents

36. A. managed             B. attempted          C. succeeded                 D. conducted

37. A. concluded           B. began                C. prevented                 D. stopped

38. A. pay                    B. owe                C. own                         D. spend

39. A. agreement           B. excitement         C. encouragement         D. statement

40. A. fight                   B. look                  C. defend                            D. protect

填空题