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

______ is not known yet.

I shall have a companion in the house after all these （ ） years．

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

Without the sun’s light （ ） the earth’s surface, no life could exist on the earth.

Mary and I （ ） the new college life soon, but Tom didn’t.

As a new graduate, he doesn’t know （ ） it takes to start a business here.

All of them are （ ） at Lana’s achievement.

What time would it be convenient _____us to meet again?

When we arrived at the airport, we were told our flight （ ）.

Neither his family nor he （ ） anything about it.

The tribe had been living in that part of the area for generations until the civil war ______.