They are talking with Tom in English.里的in为什么要用in?替换成use可以吗?还有，在什么情况下用in？

They are talking now.(对talking提问) What are they talking about? Are.they.talking(___)电话 They are talking about_____(they)birthdays. They are talking 对are talking提问 快,. We are reading w__________ they are talking. they are () the problem talking over talking about talking with talking at They are talking now,.对talking 进行提问 They are talking about their group p_____. they are talking about his______(病） Listen!What are they talking _______? What holiday are they talking about? They are talking now的提问形式 they are talking about the learning c____________ they are talking about the weather 翻译 They are talking ( ) the aniimal in the they are talking a to protect wildlife 【 】are they【 】about?they are talking about Lucy birthday party