how often,how far,how soon,how long 有什麽不同，各用于什麽提问

how often,how far,how soon,how long 有什麽不同，各用于什麽提问

how often对频度提问：how often do you visit your mother? once a week
你多长时间看你妈妈一次。 一周一次。
how far是how与形容词连用。例如：how far多远 how big多大 how deep多深 how long多长 how old多老 how sharp多锐利 how wide多宽，等提问。
how far是对路程有多远提问：how far is it to Shanghai?到上海有多远？

how long 询问持续的时间（带for或不带for）
how long have you known her(for)?你认识她有多久了
(for) 20 years. 20年了。
how 还可以和long ago连用指时间点how long ago did Bach live? 300years ago.
how soon对时间提问，等于how quickly,多快，多久
how soon can you finish the work? In two days.