I saw him _____ behind the tree, thinking.
When it comes to the human tendency to use the right hand much more often than the left hand, we seem to have __________ it from our animal ancestors, namely monkeys and chimpanzees.
Jim, I am sure __________ we met, we were at a rock concert, and since then we’ve known each other.
--- Ouch! You stepped on my toe!--- I’m sorry, I didn’t __________.
I wonder when it was __________ you came to realize __________ he said meant.
--- How come you know the accident so well?--- Well, because I was on the __________.