Choose the correct word form among A, B, C or d for each numbered gap to complete the passage

Many changes (31)....... to the world map this century. Boundaries (32) ..... as a result of world wars and foreign invasions, and many former colonies (33)...... their independence. In 1960, for instance, fifteen African countries (34) ..... independent, some of which have changed their names. This tendency to change names when countries became independent (35)...... since then: Ceylon is now Sri Lanka and the Trucial States (36)...... the United Arab Emirates. More recently, in what (37). .... the Soviet Union, even cities (38)....... by the change, the most notable example (39) ...... Leningrad, which in 1991 (40) ..... back to the
pre-Revolutionary name of St. Petersburg.
31.A. have made

B.have been made

C.are made

D.make

32.A. have redrawn

B. has redrawn

C. have been redrawn

D. were redrawn

33. A. have gained

B. gained

C. have been gained

D. gain

34. A. become

B. became

C. have become

D. has become

35. A. have continued

B. has continued

C. continue

D. continues

36. A. have become

B. becoming

C. to become

D. has become

37. A. was

B. were

C. is

D. are

38. A. have affected

B. have been affected

C. were affected

D. are affected

39. A. is

B. are

C. is being

D. are being

40. A. go

B. goes

C. went

D. has gone