Simple Sentences:
* The sky is blue. (Describing a fact)
* She is happy. (Describing a state of emotion)
* He is a doctor. (Describing a profession)
* It is cold outside. (Describing a condition)
Sentences with other parts of speech:
* The dog is playing in the park. (With a verb, "playing")
* This is my favorite book. (With a possessive pronoun, "my")
* Is that your car? (In a question)
* The answer is yes. (In a response)
* This is how you do it. (With a demonstrative pronoun, "this")
Key points to remember about "is":
* It is used for singular subjects (e.g., "the dog is")
* It is the third person singular form of "to be" in the present tense.
* It can also be used in the present continuous tense (e.g., "He is eating.").
Remember, "is" is a very common verb and it appears in many different sentence structures. By understanding its basic function, you can use it effectively in your writing and speech.