Women _______ drink more than two cups of coffee a day have a greater chance of having heart disease than those ________ don’t.
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.
Edison had built a chemical lab of ___ when he was very young.