For comparisons:
* Like: Emphasizes similarity, but not exact equality.
* _He sings like an angel._
* As if: Suggests something is happening or appears to be happening in a certain way.
* _He acts as if he doesn't care._
* Such as: Introduces examples.
* _There are many different fruits, such as apples, oranges, and bananas._
* Similar to: Highlights a resemblance.
* _The new design is similar to the old one._
* Just like: Emphasizes exact likeness.
* _She looks just like her mother._
For roles or functions:
* In the role of: Emphasizes a specific position or responsibility.
* _He appeared in the role of the king._
* As a: Indicates a general function or purpose.
* _He worked as a teacher._
* Serving as: Highlights temporary or specific duties.
* _She is serving as the president pro tempore._
For time or manner:
* While: Indicates simultaneous actions.
* _I read a book while I waited._
* When: Indicates a specific time.
* _I fell asleep when the movie ended._
* How: Describes the way something happens.
* _Tell me how you did it._
* During: Indicates the time period in which something occurs.
* _The accident happened during the rush hour._
* At the time: Focuses on a specific point in time.
* _At the time, I didn't know what to do._
For other purposes:
* Because: Indicates a cause-and-effect relationship.
* _I stayed home because I was sick._
* Since: Indicates a reason or a point in time.
* _I've been working here since 2010._
* Therefore: Introduces a conclusion.
* _The weather is bad; therefore, we'll stay inside._
Remember: The best choice will depend on the specific context and the meaning you want to convey.