“The cat cannot be seen easily.”: Is “seen” the object or part of the verb?

Question

I have problems to parse this sentence:

The cat cannot be seen easily.

I can't decide if "seen" is part of the verb and the sentence has no object or if it is the object. Or if it is a phrase (in combination with the "be") and functioning in this way as the object?

Or is both possible?

Answer 1

It is just the passive form of the verb "see"

I see the cat -> the cat is seen

I can see the cat -> the cat can be seen

I cannot see the cat -> the cat cannot be seen

Answer 2

An object is normally a noun. But a noun can be replaced by a pronoun (him/her/someone etc) or by a gerund. Your sentence contains two verb forms "cannot" and the infinitive passive "be seen". You can describe such a structure simply as verb + infinitive or, as some grammars do, say that the infinitive is object to can/cannot. As an infinitive can be seen as a verb form with noun character this view is not impossible. But it would be better to talk of infinitive in object position to have a precise description of the structure.

For learners I think it is best and simplest to see such structures as verb + infinitive, as there are hundreds of verbs that can be followed by an infinitive.