Here are some examples of words with the root "du-":
* Duet: A musical performance by two people.
* Duplicate: To make an exact copy of something.
* Dual: Having two parts or aspects.
* Duopoly: A market dominated by two companies.
* Duplex: A building with two separate living units.
Keep in mind that the meaning of "du-" can sometimes be slightly different depending on the specific word. For example, the word "durable" means "lasting for a long time", which isn't directly related to the idea of "two".