Not only John and Tom but also their sister Mary great interest in the piano lessons. A.

问题补充：

Not only John and Tom but also their sister, Mary, great interest in the piano lessons.

A. take

B. takes

C. have taken

D. had taken

答案：

A. take

(答案→)B. takes

C. have taken

D. had taken

解析：句意：不仅约翰和汤姆而且他们的姐姐对钢琴课很感兴趣。主语是not only…but also连接的时候，谓语和后面的一致，这句话就是和their sister, Mary一致，用单数，而且这里应该用一般现在时，所以选B。