keep at造句

For those with chronic depression, she said, "keep at it."

Police were called out to keep at the airport, and inspect the arriving planes.

Because this book is so important, remember to keep at least one backup of it.

How is it that the successful motivate themselves to keep at it when others fall by the wayside?

It is now known that chimps lack immunity to some human diseases, so Gombe researchers must keep at least 25 feet away.