The phrase "a long assignment" is correct and usable in written English.
It can be used to describe a task or project that requires a significant amount of time or effort to complete.
Example: "I have a long assignment due next week that I need to start working on this weekend."
Alternatives: "an extensive task" or "a lengthy project".
You're finishing a long assignment in fine fettle.
Our 9-year-old daughter recently completed a long assignment to write about New Jersey.
If you have a long assignment, prepare a large reward for when you are done, like an mp3 download or a dinner meal you never get to eat.
If you've got a long assignment of complicated problems ahead of you, take a break every half hour if it's going to take a while.
He is likely to need a long rehabilitation assignment as well, considering he was injured during his first at-bat of spring training in February.
Also, if the supervisor believes that additional time off is warranted, for example, if the local practices (not the laws) provide more vacation or for an annual home leave during a long international assignment, they may request an exception by following the process in Section 7.10.4.
Sometimes a week-long assignment cleaning up a construction site or delivering or installing store fixtures will come in.
Martens' employer offers "short-term international rotation", a year-long assignment in one of its offices abroad, and she is considering this for her next PA role.
Massey told his then boss, Chris Cramer, now a senior CNN executive, that he wanted to "bring the whole BBC disciplinary process" against Mr Thompson, but the incident "lost momentum" when Mr Massey was sent on a month-long assignment abroad.
He was sent down to the American Hockey League (AHL) in January 2008 for a month-long assignment as his play struggled, notching 5 goals and 10 points in 16 games with the Blue Jackets' minor league affiliate, the Syracuse Crunch.
He had been asked to leave his UNICEF headquarters post for a month-long assignment as the agency's chief media spokesperson in the Haitian capital.
