Explanation:

Thought is a verb in this sentence.

Subject-Verb Agreement:
In the sentence, "She thought of a wise plan," the word "thought" is the main verb. It is the action that the subject "She" (referring to a female) is performing. The verb "thought" agrees with the singular subject "She" in terms of number.

Function of Thought:
The verb "thought" in this sentence shows an action performed by the subject "She". It indicates that she came up with or conceived a wise plan in her mind. The verb "thought" is used to describe the mental process of considering, pondering, or devising something.

Other Verb Forms:
The verb "thought" is the past tense form of the verb "think". Other verb forms of "think" include:
- Present tense: think
- Future tense: will think
- Present participle: thinking
- Past participle: thought

Other Parts of Speech:
In addition to being a verb, the word "thought" can also function as a noun, referring to the process or act of thinking, or as an adjective, describing something that is the result of thought.

Example Sentences:
Here are some examples of "thought" used as a verb in different sentences:

1. I thought about what you said yesterday.
2. He often thinks before speaking.
3. They thought it would be a good idea to go hiking.

In conclusion, in the sentence "She thought of a wise plan," the word "thought" is a verb. It is the action performed by the subject "She" and shows the mental process of conceiving or devising a wise plan.