In the experiment we kept a watchful eye __________ the development and recorded every detail.

I’m familiar with you because your name ____ in our yesterday’s conversation many times.

The little boy _____on the mat ____ to his parents that blackbirds had _____their eggs on Mars．

Billy kept asking his mother whether he could go to the movies and she          at last.

The telephone _____ three times in the last hour, and each time it _____ for my sister.