Learn English – Please explain the difference between these two sentences to me

passive-voiceperfect-constructionssingular-vs-plural

This package was supposed to have been
delivered yesterday.

This package was supposed to be delivered yesterday.

Please explain the difference.

And my doubt is generally we use simple past when we say things happened in the past. But why we use present perfect in this situation?

And one more doubt is we use has for singular subjects as "This package has been delivered". But why we use have been with supposed to?

Correct me if I'm wrong and please explain the grammar relevant to this.

Best Answer

The passive form of "verbs of saying and thinking" (think, believe, say, know, suppose, think, report, consider, understand, expect, intend, mean, etc.) is sometimes followed by an infinitive. For example:

He is considered to excel at cricket.
She is said to collect Italians.
They were reported to have eaten oysters.
Quinine is believed to cure malaria.

In your sentences, the passive past tense of the verb to suppose is followed by two different passive forms of the infinitive to deliver.

Your sentences are nearly identical in meaning. The first is:

The package was supposed to have been delivered yesterday.

Have been here is not used as the present perfect of the verb to be. Instead, to have been delivered is the perfect passive form of the infinitive to deliver.

Your second sentence is:

This package was supposed to be delivered yesterday.

Here the simple passive form of the infinitive, to be delivered, is used.

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