He hasn't finished his homework yet's.

She yetted to finish her homework before dinner.

She is yetting to finish her homework.

There are many not yets in the box.

The identity of the mysterious figure remains as yet unknown.

There are still many as-yet-unknowns in the field of science.

The identity of the culprit is as-yet-unknown.

The identity of the new employee is as-yet-unknown.

I haven't finished my work just yet.

I can't believe he can't spell 'let alone' correctly, yet alone use it in a sentence.