______ at failing in the math exam, John wouldn’t like to talk about it to his parents.
When I was a child, I __________ watch TV whenever I wanted to.
Since nobody gave him any help, he __________ have done the research on his own.
The children __________ lost in the woods; otherwise, they would have been at the lakeside camp as scheduled.
-Where did you get this book?-I picked it up from a second-hand bookshop if you __________ know.
Don't be angry with us. We __________ with you together, but we were busy with our final reports when you called in.