There are so many viruses on the Internet. If ______ accidentally, the viruses may make your computer break down.

Jimmy has invented a set of equipment independently to produce valuable chemicals with waste materials ______ by others.[ ]

Bob______nearly two hours doing his workyesterday

We have to write a description of the street ______ we live and give it to the teacher tomorrow.

Our team ________ their team in the match, that is, our team ________ the match.[ ]