51. Don’t put your cell (手机) _____ the edge of the table, or it will fall off

52. The struggle against sand storm will not end _____ victory unless we pay much attention to the balance of nature.

53. Our music teacher often enjoyed _____ playing the violin in his spare time.

54. The football fans cheered their team _____ the entrance _____ the field.

55. All the students envied him _____ having succeeded in the TOFEL test.

56. In the college entrance examination, one of my students did very well _____ poor handwriting.

57. I am sure you will excuse me _____ not telling you ahead of time.

58. It is said that a collection of paintings by David is _____ exhibition at the Museum.

59. During the whole TV interview, the middle-school girl student never once looked me _____ .

60. Officially the Frenchman is in charge, but __________ his secretary does all the work.