As we all know, apples are sold by ____ weight, and socks are sold by _______dozen.

Though she is _______ at home, she never feels ________.

Have you heard of Earth Day ?—-Yes . The first Earth Day ______ in 1970 to educate us to protect our planet .

Many visitors come to Beijing because it is ________ city.

He looks so tired ______ too much computer work.[ ]