There is ______ “u” and ______ “s” in the word “use”.
These English words are important, please _____.
--- Where is Mary?--- She ____ to Harbin.
I’ve ____ met her before, so I don’t know her.
--- ____ have you been a member of Greener China?--- For two years.
--- Have you ____ your key?--- No, I’ve ____ for it everywhere, but I can’t find it.