Simple:
* The company proposed a new marketing strategy.
* The government proposed a law to increase taxes.
* He proposed to his girlfriend on the beach.
With context:
* The architect proposed a modern design for the new library.
* The committee proposed a series of amendments to the constitution.
* They proposed a compromise to resolve the conflict.
In different tenses:
* The project was proposed last year. (past tense)
* She is proposing a new solution to the problem. (present continuous tense)
* We have proposed several ideas for improvement. (present perfect tense)
With different meanings:
* The proposed changes will affect all employees. (suggested, planned)
* The proposed marriage was met with resistance from her family. (suggested, offered)
Remember that "proposed" can be used as both a verb (action) and an adjective (describing a noun). Choose the right form based on the context of your sentence.