MODAL VERBS SHOULDN'T HAVE A PREPOSITION AFTER THEM:

In our Skype English classes many students incorrectly say ‘he can to come at 8’ or ‘they must to go running this evening’. However, all modals except for ‘ought to’ are followed by the base form of a verb (or infinitive) with no preposition after it. Some examples:

• I should go to visit them.
• I think it will rain tomorrow.
• Things could have been better.
• Someone may have seen them.
• They might be home tomorrow.
• They may be late.
• They would have known if they had gone to the seminar.
• He can come by anytime.
• You must get that project finished.
• I shall hand-in the paper on time.

Remember that modal verbs can’t be switched from tense to tense like normal verbs. For example, we cannot say ‘we musted do the homework’ or ‘I will must to study Norwegian’.

Also, modal verbs cannot appear together in the same sentence. Many people say ‘I will can go out tonight’. This is very incorrect. Since ‘will’ and ‘can’ are both modal verbs we need to use ‘to be able to’ after ‘will’. So the correct sentence would be ‘I will be able to go out tonight’. This would translate as ‘Yo podré salir esta noche’.
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