There seems to be two causes as I try to figure out __________ that prevents so many children from being as happy as before.
It also awards me _____ opportunity to learn American culture at _____ first hand.
We ________ last night, but we went to the concert instead.
.---I’m terribly sorry to have put you through so much trouble. --- ________. I know you didn’t mean to.
A study shows that students living in non-smoking dormitories are less likely to ________ the habit of smoking.
.--- ______,he knows a lot of things.