Question

Fill in the blanks with suitable modals-
1. The teacher said that we ......... not use red ink.
2. We ........... think carefully before our actions.
3. Get down the train carefully, lest you ........ fall.
4. We ........ to spend our money carefully.

Answer 1

1) should

2) should

3) would

4) have

Answer 2

1. The teacher said that we should not use red ink. (should is used to show an expectation or a recommendation)

2. We should think carefully before our actions. (should is used to show obligation)

3. Get down the train carefully, lest you should fall. (here should is used to give an advice)

4. We ought to spend our money carefully. ( Ought to implies a strong commitment)

• Modal verbs are the verbs that are followed by a main verb.They are helping verbs that cannot standalone as a main verb.  
• We use them to show obligation, willingness, ability, possibility etc.