48. Although I spoke to him many times, he never took any _____ of what I said.

　　A) notice

　　B) attention

　　C) consideration

　　D) warning

　　49. It is no easy thing to _____ the meaning of every idiom in English.

　　A) get by

　　B) get in

　　C) get on

　　D) get at

　　50. The book only _____ the causes of the war and does not do justice to the influence of the slave trade.

　　A) counts on

　　B) touches on

　　C) takes on

　　D) pulls on

　　51. We must take a firm _____ against the lowering of educational standards.

　　A) stand

　　B) place

　　C) position

　　D) reason

　　52. It never _____ my mind that he might refuse the request.

　　A) passed

　　B) filled

　　C) crossed

　　D) occurred

　　53. At the sight of the police officer, the thief _____.

　　A) got to his feet

　　B) took to his heels

　　C) rose to his feet

　　D) dragged his heels

　　54. The guide told us that an incident _____ here in 1925.

　　A) took place

　　B) was taking place

　　C) had been taking place

　　D) had taken place

　　55. _____, one must understand mathematics.

　　A) A good scientist

　　B) In order to be a good scientist

　　C) It's a good scientist

　　D) Being a good scientist