The lively boy suddenly appeared to be ________ quiet, so his mother knew something unusual must have happened.

She put some soil in the box, then sowed the seeds carefully, and covered it with more soil. _______ she kept the box in the shade.

Since Tom ___downloaded a virus into his computer, he can not open the file now．

At first, we didn't know about Tom. But ____, we came to know that he was an honest boy.

Nelson Mandela, former president of South Africa, devoted himself        to making the black and white equal.