I'm teaching ESL, and I came across a question from one of my students that I don't know how to answer. Using the form "{subject} {verb} {adjective} {infinitive phrase}" we've been going over sentences such as "I was happy to help you." (More specifically, "I helped you. I was happy. -> I was happy to help you.")
One of my students then suggested "I was tired to do my homework."
Now, as a native English speaker, I know that this is wrong. I'm even college educated and actually trained in ESL (which included grammar classes)… and yet, I have no idea WHY this is wrong. It SEEMS to fit the form our textbook was teaching ("I did my homework. I was tired." -> "I was tired to do my homework.") and yet I know it's wrong.
What's the difference? Why doesn't this work?
Best Answer
Let's change the main verb to "see". All the following adjectives accept an infinite
I was happy to see her
I was sorry to see her
I was surprised to see her
I was disappointed to see her
5a . I was sad to see her (go)
5b. I was saddened to see her
‘I was saddened to see their lack of commitment.’
Incidentally, mad in British English usually means "crazy", so the speaker could be complaining:
“I must have been mad to see her, whatever was I thinking?”
I was impatient to see her
I was anxious to see her
BUT NOT
Similarly, it is equally ungrammatical to say: “I was bored to do my homework”
Google Books has innumerable results for bored to death, and bored to tears but none for was bored to do and only 4 instances for was bored to see And yet, bored is also a feeling or an emotion. A handy list of adjectives ending in -ed and -ing which may help the OP in his ESL lessons
In sentence number 10, the speaker probably wanted to say they were too tired to meet someone, "too" often carries a negative meaning.
As a result, I didn't do my homework.
However, using tired alone (without the adverb too) works as the reason for doing or not doing something.
to go to bedto stop for a restto see himto do my homeworkThe same is true for the following synonyms of tired: weary, exhausted, sleepy, drained, burnt-out / burned-out.
REVISED
I found an interesting older question on EL&U which mentions the usage of infinitives after adjectives. It doesn't specifically answer the OP's question but I consider it useful nevertheless.
To infinitive used after adjective.
The following is a short excerpt from @Araucaria's answer.
Addendum
Many users have repeatedly pointed out (see comments) that the adjective annoyed is used with the to-infinitive. The following pattern, ANNOYED AT + GERUND as in: I was annoyed at doing my homework, sounds far better to my ears; however, after searching a bit, I did find a few examples in the Oxford Learners' Dictionaries of annoyed + to-infinitive (to my consternation ☺).