Was it in 2002 __________ he was still at middle school __________ the boy became expert at computer?
Dr. Black is a professor of chemistry. _______, he is a famous writer.
The new invention may __________a lot of changes in our daily life.
It _______ them three years to build this road.
I wanted _______ you for your last letter.
He missed his mother very much and ________ crying.