used to + do："過(guò)去常常"表示過(guò)去習(xí)慣性的動(dòng)作或狀態(tài)，但如今已不存在。
Mother used not to be so forgetful.
Scarf used to take a walk. (過(guò)去常常散步)
be used to + doing： 對(duì)……已感到習(xí)慣，或"習(xí)慣于"，to是介詞，后需加名詞或動(dòng)名詞。
He is used to a vegetarian diet.
Scarf is used to taking a walk.(現(xiàn)在習(xí)慣于散步)
典型例題
---- Your phone number again? I ___ quite catch it.
---- It's 69568442.
A. didn't B. couldn't C. don't D. can't
答案A. 本句雖沒(méi)有明確的時(shí)間狀語(yǔ)，但從語(yǔ)意上看 出，在聽(tīng)的時(shí)候沒(méi)有聽(tīng)懂這個(gè)動(dòng)作發(fā)生在過(guò)去，因此應(yīng)用過(guò)去時(shí)。