A left-luggage office is a place where bags ________ be left for a short time, especially at a railway station.
My brother tried ___, but still he couldn't work out this maths problem.
He seemed as if he ___ his homework when his mother came in.
The poster says that a writer and poet ___ to give us a talk on English next week.
How this kind of plant can be ____ in a special way is still unknown to us.
If I ___ free tonight, I'll go to the cinema with you.