1) Antibiotics sould (take) regularly, or they aren't effective in fighting bacteria or viruses.

2) Farm equipment had to (pull) by horses before the invention of the tractor.

3) A: Teacher, can you (postpone) tomorrow's exam to the next day? B: No, it can't (postpone) this time.

4) This plant shouldn't (keep) in direct sunlight, or it will lose its leaves.

5) Parents should (warn) their children of dangers all the time.

6) Why don't you ask the boss for permission? He may (allow) you to leave early.

7) Aspirin can (use) as a painkiller or fever reducer.

8) Some birds, such as ostriches, cannot (fly).

9) All the staff worked hard, but they couldn't (finish) yesterday,

10) Turkey is on a major earthquake belt, so contractors shouldn't (allow) to build very tall building.