1.hear of,表示‘听说’,后面加sth/sb
Have you ever heard of the Great Wall?
你听说过长城吧?
2.hear from sb.‘收到...的来信’
I heard from my father last week.
我上周收到老爸来信.
3.hear‘听到’,‘听说(后加宾语从句)’
I hear a girl singing.我听到一个女孩在唱歌.
I heard that you can cure cancer with this medicine.我听说可以用这要来治癌症.