It worried her a bit ________her hair was turning gray.
Last night, there were millions of people ______ the opening ceremony live on TV.
______ carefully if any change occurs when doing experiments in the lab.
Jane is in a hurry because the train to the airport leaves ______ half an hour.
--- Hi, let's go skating. --- Sorry, I'm busy right now. I ______ in an application form for a new job.
Some animals carry seeds from one place to another, ______ plants can spread to new places.