48. _C_ one time， Manchester was the home of the most productive cotton mills in the world. [at one time 曾经，一度]
A On B By C At D Of
49. _A_ it or not， his discovery has created a stir in scientific circles.
A Believe B To believe C Believing D Believed
believe it or not 信不信由你。 creat a stir 引起轰动。
50. Mr. Morgan can be very sad _C_， though in public he is extremely cheerful.
A by himself B in person C in private D as individual
in public 在公众面前; in private 私下单独人的时候。
10. Walter offered us a lift when he was leaving the office， but our work _A_， we declined the offer. [declined v. 婉言谢绝]
A not being finished B not having finished
C had not been finished D was not finished
42. A survey was carrie3d out on the death rate of new-born babies in that region， _D_ were surprising. [survey 调查]
A as results B which results C the results of it D the results of which
51. All flights _D_ because of the snowstorm， many passengers could no nothing but take the train. [having been canceled 这里是独立主格作原因状语]
A had been canceled B have been canceled
C were canceled D having been canceled