Question

join using infinitives The students were very excited. They did not hear the instructions properly.

Answer 1

We have two sentences given in the question :-

The students were very excited. They did not hear the instructions properly.

As per the question, these two sentences are to be joined using an infinitive. An infinitive is a phrase that has the word "to", followed by the verb.

Since the above sentence is concerned with the students not hearing the instructions out of excitement, it can be framed as follows :-

The students were too excited to hear the instructions properly.

As you can see, the new sentence has the infinitive to hear that joins both of the previous sentences while keeping the original meaning intact.

Answer 2

Here is the correct answer along with its explanation:

The students were too excited to hear the instructions properly.

Explanation

'To hear' is infinitive.

The 'too+adjective+to' structure is used to say that something or someone is more than good, necessary, possible, etc. In simple words, 'too+adjective+to' structure is used to mean the negative sense of the given sentence. For example the meaning of the sentence 'You are too clever to be cheated.' is 'You are so clever that no one can cheat you.'