People try to avoid public transportation delays by using their own cars, and this ______ creates further problems.
If you are in any doubt as to _____ you should be doing these exercises, consult your doctor.
—When can I come for the photos? I need them tomorrow afternoon. —They_______ be ready by 12:00.
Was it _____ she heard with her ears ____ really made her frightened?
Beneath our feet _____ that our life depends on for food and clothing.
We must treasure every minute because _____ time is _____ forever.