--Why has he been staying at home these days? --He ___________ since a month ago.
The charity sale our school organizes every year has taught us much that we would never have________ learned in class.
---Harry, we want to know your view about the reform being carried out in our school.---OK. I ________ to that.
Tom hid himself behind the door, _________ he could hear the steps of his mother clearly.
Having a trip abroad is certainly good for the old couple, but it remains _______ whether they will enjoy it.
---Excuse me, dad, but I’m going to the club to meet my friends in the football team. ---OK. _______ .