Meaning: He noticed the winged animal in the space above the earth's atmosphere.
Choice of Words: The word "bird" refers to a warm- blooded, egg-laying vertebrate animal that has wings. "The sky" is the space above the earth's atmosphere.
Alternative Expressions
He was watching the bird in the sky.
Meaning: This means that the person has been looking at the bird for a while now and is still watching it.
Choice of Words: This sentence is also written in present tense, but it uses the continuous tense to indicate that the action is ongoing. The subject is still "He" and the verb is "was watching". The object of the sentence is still "the bird" and "in the sky" is still a prepositional phrase that describes where the bird is located.
He had seen the bird in the sky.
Meaning: This means that the person looked at the bird at some point in the past, but is not necessarily looking at it now.
Choice of Words: This sentence is written in past tense and indicates that the action happened at some point in the past. The subject is still "He" and the verb is "had seen". The object of the sentence is still "the bird" and "in the sky" is still a prepositional phrase that describes where the bird was located.