I don't know

1. Used in response to a question or command in which the target person does not know the answer to or how to respond.
2. Used to indicate that one is speculating (often used sarcastically when stating the obvious).
3. Used to express exasperation or incredulity about a given situation or person.
4. Used other than figuratively or idiomatically: see I, don't, know.

that

• Conj

  1. Introducing a clause that is the object of a verb, especially a reporting verb or verb expressing belief, knowledge, perception, etc.
  2. Introducing a clause that is the subject of a verb, especially the 'be' verb or a verb expressing judgement, opinion, etc.
  3. Introducing a clause that is the subject of a verb, especially the 'be' verb or a verb expressing judgement, opinion, etc.
  4. Introducing a clause that complements an adjective or passive participle.
  5. Introducing a clause that complements an adjective or passive participle.
  6. Introducing a subordinate clause modifying an adverb.
  7. Introducing a clause that describes the information content of a preceding reporting noun.
  8. Introducing — especially, but not exclusively, with an antecedent like so or such — a subordinate clause expressing a result, consequence, or effect.
  9. Introducing a subordinate clause that expresses an aim, purpose, or goal ("final"), and usually contains the auxiliaries may, might, or should: so, so that, in order that.
  10. Introducing a premise or supposition for consideration: seeing as; inasmuch as; given that; as would appear from the fact that.
  11. Introducing an exclamation expressing a desire or wish.
  12. Introducing an exclamation expressing a strong emotion such as sadness or surprise.

• Det
• Pron
• Adv
• Noun

I

• Pron

  1. The speaker or writer, referred to as the grammatical subject, of a sentence.
  2. The speaker or writer, referred to as the grammatical object, of a sentence.

• Noun
• Character
• Num
• Noun
• Intj

don't

• Verb

  1. do not (negative auxiliary)
  2. does not
  3. Used before an emphatic negative subject.

• Intj
• Noun
• Contraction

know

• Verb

  1. To perceive the truth or factuality of; to be certain of; to be certain that.
  2. To be or become aware or cognizant.
  3. To be aware of; to be cognizant of.
  4. (obsolete) To be acquainted (with another person).
  5. To be acquainted or familiar with; to have encountered.
  6. To be acquainted or familiar with; to have encountered.
  7. To experience.
  8. To understand or have a grasp of through experience or study.
  9. To be able to distinguish, to discern, particularly by contrast or comparison; to recognize the nature of.
  10. To recognize as the same (as someone or something previously encountered) after an absence or change.
  11. To have knowledge; to have information, be informed.
  12. To be able to play or perform (a song or other piece of music).
  13. To have indexed and have information about within one's database.
  14. To maintain (a belief, a position) subject to a given philosophical definition of knowledge; to hold a justified true belief.

• Noun
• Noun
• Particle