A later word may need an earlier clue

Read this sentence:

The animal didn't cross the street because it was too tired.

What does it mean?

You know it means animal. A street cannot be tired. To understand the later token it, you used the earlier token animal.

Five other words sit between them. In a longer passage, the useful clue might be fifty or five hundred words back.

That is the problem. A machine must handle a sentence of unknown length while keeping earlier clues available for later words.