If you write something and send it immediately by email, which you ___later regret, there is no chance for second thoughts．

Where is your father, Helen—He is trying to a new shower in the bathroom.

Sam _____ some knowledge of the computer just by watching others working on it.[ ]

She is always thinking more of herself, seldom, ________, offering to help others.

While I was standing ______the window， I saw several boys running _______the street.