used to / be used to
used to + do："过去常常"表示过去习惯性的动作或状态，但如今已不存在。
Mother used not to be so forgetful.
Scarf used to take a walk. (过去常常散步)
be used to + doing： 对……已感到习惯，或"习惯于"，to是介词，后需加名词或动名词。
He is used to a vegetarian diet.
Scarf is used to taking a walk.(现在习惯于散步)
典型例题
---- 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. 本句虽没有明确的时间状语，但从语意上看 出，在听的时候没有听懂这个动作发生在过去，因此应用过去时。
大学英语四级语法知识：be going to / will
be going to / will
用于条件句时， be going to 表将来
will 表意愿
If you are going to make a journey, you'd better get ready for it as soon as possible.
Now if you will take off your clothes, we will fit the new clothes on you in front of the mirror.
大学英语四级语法知识：mean to doing/to do
mean to doing/to do
mean to do 打算、想
mean doing 意味着
I mean to go, but my father would not allow me to.
我想去，但是我父亲不肯让我去。
To raise wage means increasing purchasing power.
赠加工资意味着增加购买力。
From:https://www.zgghmh.com/CET-4/20001541.asp