-What are they doing? -They are talkingthe phonetheir life.A. on; aboutB. in; aboutC. to;

问题补充：

-What are they doing?

-They are talkingthe phonetheir life.

A. on; about

B. in; about

C. to; about

D. on; on

答案：

(答案→)A. on; about

B. in; about

C. to; about

D. on; on

解析：通过电话交谈可用介词on，谈论某事可用介词about，故本题选A。