Here, 'back' names a body part. It functions as a noun.

'Your' modifies the noun 'pen' to show ownership. It is a possessive adjective (or determiner).

'Little' indicates the amount of patience (an uncountable noun), making it an adjective of quantity.

Here, 'outside' modifies the noun 'wall', describing its position. It functions as an adjective.

'Thought' expresses a mental action. Therefore, it is an action verb.

Distributive pronouns refer to persons or things one at a time. 'Neither' (meaning not the one nor the other) is a distributive pronoun.

Here, 'address' names the location details. It functions as a noun.

Here, 'address' denotes the action of dealing with the problem. It functions as a verb.

'Rich' is an adjective functioning as a noun (meaning 'rich people'). This is called a nominal adjective or substantive adjective.

Here, 'like' expresses a preference or action. It is the main verb of the sentence.