— What do you usually do in your spare time, playing the violin or the piano?

— I do ______ of them. I practice singing with some volunteers. [ ]

A.either

B.both

C.all

D.neither

我国的现有武装力量有（）部分组成

A、陆军

B、海军

C、空军

D、第二炮兵

E、武装警察部队