The reason_________ he didn't come was _________ he had to take care of his sick mother.
--- I called you last night, but nobody answered the phone. --- Sorry, ________.
We need to strike a ______ between the needs of the community and the rights of the individual.
We ______ while Mr. Evan read the exam results.
You may ______ your teachers for help when you have problems.
Was it______ Tom’s carelessness______ your keys were lost?