Formal:
* Parfois ennuyeux/ennuyeuse: This is the most direct translation. "Parfois" means "sometimes" and "ennuyeux/ennuyeuse" means "boring." This option is appropriate in formal settings.
Informal:
* Un peu chiant/chiante: This is a more informal and slangy way to say "boring." "Chiant/chiante" is a colloquial term for "boring" and can be considered somewhat rude.
* Pas toujours passionnant/passionnante: This means "not always exciting" and is a more polite way to say "sometimes boring."
More specific:
* Parfois un peu répétitif/répétitive: This means "sometimes a bit repetitive" and can be used to describe something that is predictable and lacks variety.
* Parfois un peu monotone: This means "sometimes a bit monotonous" and can be used to describe something that is dull and lacking in interest.
Example sentences:
* Ce film est parfois ennuyeux. (This movie is sometimes boring.)
* Ce travail est un peu chiant. (This job is a bit boring.)
* Les cours sont pas toujours passionnants. (Classes aren't always exciting.)
* Le voyage était parfois un peu répétitif. (The trip was sometimes a bit repetitive.)
* Sa voix est parfois un peu monotone. (His voice is sometimes a bit monotonous.)
Remember to choose the phrase that best fits the specific situation and your desired level of formality.