Which parts of speech should never be used to start a sentence?

There's no strict rule about which parts of speech can't start a sentence. However, some parts of speech are less common at the beginning and can sound awkward or unnatural:

* Conjunctions: Words like "and", "but", "or", "so" are typically used to connect clauses, not to start sentences.

* Example: "And the cat sat on the mat." (Sounds more natural as "The cat sat on the mat.")

* Prepositions: Words like "on", "in", "at", "to", "from" are usually used to show the relationship between a noun or pronoun and another word.

* Example: "In the garden, a butterfly landed." (Sounds more natural as "A butterfly landed in the garden.")

Important: These rules are not absolute! Sometimes, starting a sentence with a conjunction or preposition can be used for emphasis or stylistic effect.

Here are some examples of when it's perfectly acceptable to start a sentence with a conjunction or preposition:

* Emphasis: "But I told you, it wouldn't work!"

* Short, punchy sentences: "On the table lay a single rose."

* Creative writing: "And so the adventure began."

Ultimately, the best way to determine whether a sentence sounds good is to trust your ear! If it sounds natural and flows well, then it's probably fine.