________ you stepped into the lab with your shoes on? You’re supposed to take them off before you enter it. I told you so!
It is ten years since we ________ each other. We have been working together.
I asked my English teacher and he replied with a ________look.
The plane takes off at 6:00 p.m. So I have to arrive at the airport ________ 5:30 p.m. at the latest.A after B. since C. until D. by
--How long ________ as an assistant here?-- Ever since I finished middle school.
--Forgive me for hurting you by saying so.--________