I'm sorry to hear that.为什么要加to?

I'm sorry to hear that.为什么要加to? i'm sorry (to hear)that为什么填to hear I'm sorry to hear that .作文 I‘m sorry to hear that. 翻译.I'm sorry to hear that. I'm very sorry to hear that. I'm sorry to ________(hear) that i'm sorry to hear that .that可以换成this I`m sorry to hear “I'm sorry to hear I am sorry to hear that you're not feeling well,为什么加that? I'm sorry to hear that.的意思!