* Formal: The research team has undertaken a comprehensive study of the effects of climate change on coastal ecosystems.
* Action-oriented: After careful consideration, the company undertook a major restructuring effort to improve efficiency.
* Past Tense: The construction project was undertaken by a team of experienced engineers.
* Passive Voice: The task was undertaken with great care and precision.
* With a Noun: The arduous journey was a challenge undertaken with courage and determination.
Note: "Undertaken" is the past participle of the verb "undertake," which means to start or attempt something, especially something that is difficult or challenging.