Have you ever waited for your bus at a bus stop for a very long time, only ______ by two or more buses arriving together?

(单选题)（ ） (单选题)（ ） (单选题)—Mind if I open the door now?—______. (单选题)Many netizens are impressed with the excuse given by a teach (单选题)—Is everyone here, Jonathan?—No, sir. Mille is absent. She _ (单选题)It is the teacher-and-student interaction ______ students sh (单选题)—How long do you expect it ______ before the African can kee (单选题)China is sure to further reduce the poor rural population by (单选题)Massive open online courses provide a wonderful model of ___ (单选题)—I’m sorry I broke your cup.—______. Go ahead.