Choice of Words: Keys are small objects that we use to lock or unlock something. To remember is to bring back into one's mind something learned, experienced, or known.
Alternative Expressions
I can't forget my keys.
Meaning: This means that the speaker is unable to forget their keys. They always remember where they are.
Choice of Words:I is the pronoun that refers to the speaker. Can't is a contraction of the words cannot which means not able to do something. Forget means to not remember something. My shows that the keys belong to the speaker. Keys are the objects that the speaker can't forget.
My keys are always on my mind.
Meaning: This means that the speaker always thinks about their keys. They are never far from their mind.
Choice of Words:My shows that the keys belong to the speaker. Keys are the objects that are always on the speaker's mind. Are is the verb that connects the subject and the rest of the sentence. Always means all the time, without exception. On means in or at a particular place or position. Mind refers to the speaker's thoughts and memories.