54. A. mean          B. have             C. know           D. seem

53. A. quickly         B. completely       C. maybe          D. almost

52. A. the            B. a               C. / (不填)         D. some

51. A. for            B. at              C. in              D. on

50. A. laughs         B. shouts          C. smiles           D. calls

49. A. horn           B. bear           C. bag              D. driving-seat