Wearing tight shoes is foolish. It deforms the feet.

121. In imperative sentences the subject (you) is commonly omitted: as,—“Shut the door.”

Note. The subject I is sometimes omitted in wishes (as, “Would he were here!” for “I would that he were here”). So also in “Thank you,” “Pray tell me” (compare prithee for “I pray thee”).

Expressions like “Canst tell?” (for “Canst thou tell?”), “Art there?” (for “Art thou there?”) are common in poetry and older English. These come from the gradual wearing away and final disappearance of the pronoun thou (canst thou, canstow, canstë, canst).

Possessive Case

122. The possessive forms my, thy, our, your, her, and their are used when a noun follows; mine, thine, ours, yours, hers, and theirs cannot be followed by a noun, and stand commonly in the predicate. His may be used in either way.

My brother has arrived.The fault is mine.
Our work is done.Those seats are ours.
I have torn your glove.This pencil is yours.
Their turn has come.That field is theirs.
His hair is black.The book is not his.

Examples of mine, yours, etc. not in the predicate are:

In such cases the pronoun is always emphatic. The construction is chiefly colloquial.