I thought "it" is used to comment made by me and "that" is used to comment made by another person. But why is "that" used here?
Native speaker’s answer
Rebecca
"That" and "it" would both be correct to use in this sentence, but "that" and "it" have different nuances. She uses "it" because "it" sounds less confrontational and more neutral, which is more appropriate to use because she is talking to her boss. "That" sounds more aggressive and straightforward, which is not an appropriate way for her to talk to her boss. Ex: A: You need to do your homework! B: Stop saying it, I'll do it now! (This response is still somewhat rude, but "it" here is less rude than if "that" were used) Ex: A: You need to clean your room! B: Don't say that! I'll do it this weekend. ("That" sounds rude and aggressive here)