They must have been here the day before yesterday,＿＿＿＿?

_______in thought, he didn’t notice that the teacher was right in front of him [ ]

Our company has really taken off and is ______ to make much money this year.

Do you know _______________________ won high click rate in micro-blogs?—It was the teachers’ wonderful chorus in the New Year’s gala.

Hearing their grandpa was coming, they began to ________ the work to prepare for a nice dinner.