– How do you learn English Tony? – I usually practice English chatting with my American

问题补充：

– How do you learn English, Tony?

– I usually practice English chatting with my American friends.

A. in

B. with

C. on

D. by

答案：

A. in

B. with

C. on

(答案→)D. by

解析：句意：托尼，你是如何学习英语的？我通常和我的美国朋友聊天来练习英语。介词by表达方式，即by引导的介词短语做方式状语；故选D。