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17 / 06 / 2004

REVIEW OF MODAL VERBS-4 --> MUST and HAVE TO: meaning and examples

Good morning.

Yesterday we looked at May and Might and today we will look at Must and Have to, two modal verbs that add Obligation to the main verb.

Example 1 (statement with no obligation):
I go to work every morning.

Example 2 (obligation):
I have to go to work every morning.

Example 3 (obligation):
I must go to work every morning.

Many textbooks mark a clear distinction between these two modal verbs of obligation. They say that have to indicates external obligation and must indicates internal obligation (from yourself).

Example 4 (external obligation):
I have to work every morning. (I'm obligated by my boss, society, etc.)

Example 5 (internal obligation):
I must call Anne. (Because it has been a long time since I've talked to her and I would really like to know how she is.)

In reality, however, native speakers don't always follow this tendency and I therefore usually tell students not to worry about this difference.

There are a few other things to remember.

1) Must should NEVER include the particle to. This is a very very very very common error amongst students; I often hear students say sentences like **I must to go to work.** It sounds horrible.

2) The negative of must is must not or mustn't. However, the negative of have to is don't have to. You cannot say **haven't to**. This is also a very common error.

3) The past of have to is had to, or didn't have to in the negative. There is no equivalent past for must, so it's past is also had to, or didn't have to in the negative.

Example 6 (present):
I must call Anne.

Example 7 (past):
I had to call Anne.

There is one last VERY important point. The negative of have to (don't have to) indicates lack of obligation, NOT negative obligation.

Example 7:
I don't have to call Anne.

This means that I don't have the obligation to call Anne. I can if I want to, but I'm not obligated to.

The negative of must (mustn't) indicates negative obligation.

Example 8:
I mustn't call Anne.

Example 8 means I have the obligation NOT to call her. In 7 I had a choice, in 8 I am being obligated not to do something.

If you have any questions about must and have to, please don't hesitate to contact me.

Have a good day!