...they think it was their conversation that gave them their information about each other. (Para. 3)
it is/was ... that: a sentence pattern that is used to give special importance to one part of a sentence
It was Harry that told the police. 是哈里报了警。
It is the body language that tells others about who you are. 是形体语言告诉了人家你是干什么的。
n. 图案,式样,典范,模式,型
v. 以图案