Have you heard back from them?请问这里的back是什么词性?当回信讲?

Have you heard back from them?请问这里的back是什么词性?当回信讲? Have you ever heard have you heard have you have you heard Have you heard anything back from Mr. Mu on Bo Zhu?翻译一下是什么意思,谢谢! have heard that love to come back Have you heard from ___recently? Have you heard it before? have you heard什么意思 you have probably heard itbefore Have you ever heard of Al Martino?Not many people know his name nowadays but back in 1952 he made Have you ever heard of Al Martino?Not many people know his name nowadays but back in 1952 he made heard of 同义词have you heard of Bali?同义句 I have heard a lot of good things about you( )II have heard a lot of good things about you( )I came back from abroad.答案是since ,为什么不用before? heard 和heard of的区别?have you heard that?have you heard of that?有啥分别? Have you heard about the Prime Minister? Have you heard the amazing news 急 Have you heard from your parents r____? Have you ever heard ____ the Disneyland