The phrase "are complemented by a" is correct and usable in written English.
It can be used when describing how one element enhances or completes another in a sentence.
Example: "The main dish is complemented by a selection of fine wines that enhance the overall dining experience."
Alternatives: "are enhanced by a" or "are supported by a".
The very adjustable seats are complemented by a steering wheel that both tilts and telescopes.
But all these are complemented by a rising swell of apps for shooting, editing and sharing.
Additionally, the sessions of training and writing are complemented by a panel discussion.
The labs are complemented by a range of flexible teaching spaces that can be configured for smaller and larger groups.
These are complemented by a handful of watercolors, prints and decorated letters, the latter adorned with deft watercolor sketches of flowers or fruit.
The banal organizing principles of "Blue Planet" — the cycle of seasons, day flowing to night and back — are complemented by a pervasive tedium in the montage.
His boyish features are complemented by a physical agility and alertness that make it easy to understand why he has been anointed Hollywood's latest adventure hero.
"The unfortunate events of 2011 notwithstanding, those structural advantages are complemented by a real culture of operational excellence, which isn't often the case in media or digital companies".
Fresh cherry aromas are complemented by a pleasant bitterness, from which the name of the wine is derived ("amaro" is Italian for bitter).
There are still enough stars to light the desert sky, but they are complemented by a number of willing role players who will provide defense (Tayshaun Prince), rebounding (Nick Collison), shot blocking (Tyson Chandler) and 3-point shooting (Mike Miller).
At A La Carte Culinary Services in Lynbrook, owned by Polly Talbott, the adult classes are complemented by a junior chef series on Saturdays for children 8 to 17.
