问题补充：
— I often chat with my friends on the Internet.
— You are so smart! Will you please tell me?
A. how to do
B. how to do it
C. how to use
D. when can I use it
答案：
A. how to do
(答案→)B. how to do it
C. how to use
D. when can I use it
解析：考查“疑问词+动词不定式”。宾语从句必须为陈述语序，且句中连词在句中充当一定的成分，故答案选B。意为“怎么做”。
