It was Thomas Edison that （ ） the electric lamp.

Scientists now have some surprising answers about whether brain power（ ）as we get older.

（ ） the past year as an exchange student in Hong Kong, Linda appears more mature than those of her age.

Only when （ ） in the afternoon （ ） able to leave.

He （ ） yesterday morning, and would stay for three days.

A new technique （ ）, the output as a whole increased by 20 percent.

“You are too self-centered.It’s high time you （ ） that you are not the most important person in the world,” Edgar said to his boss angrily.

Neither his family nor he （ ） anything about it.

（ ） some mammals came to live in the sea is now known.

To be frank, （ ） is a great relief to have the task fulfilled in so short a time.

The whole class couldn’t help _____ when they saw the haircut of their new classmate.

Please remember（ ） these letters on your way to the station.