"hard mission" is correct and usable in written English.
You can use this phrase when you are describing a task that is difficult or challenging. For example, "This expedition will be a hard mission, but I'm confident that we will succeed."
"I think it's going to be a hard mission," Bolt, who will turn 26 on Aug. 21, said Thursday.
Though pleiotropy, which refers to the phenomenon of a gene affecting multiple traits, has long played a central role in genetics, development, and evolution, estimation of the number of pleiotropy components remains a hard mission to accomplish.
Getting this step right is a very hard mission, first, talk to his REAL friend, ask him what he likes, but remember, never make it stay too strange.
"They look to us to do the very hard missions in very difficult conditions".
The nature and whereabouts of most of those "hard missions," however, remain unknown to Americans.
The game's hardest mission, bar none.
The harder mission is to cement democracy and remake Iraq so that dictators of his ilk cannot re-emerge.
It was a harder mission today, because it meant overlooking the cuts to tax credits that are going to start hitting the working poor next year.
PYONGYANG, North Korea (AP) — South Korean President Moon Jae-in began his third summit with North Korean leader Kim Jong Un on Tuesday with possibly his hardest mission to date — brokering some kind of compromise to keep North Korea's talks with Washington from imploding and pushing ahead with his own plans to expand economic cooperation and bring a stable peace to the Korean Peninsula.
Those are amorphous concepts, not rock-hard missions.
This "wear-and-forget" sensory system is also designed for stressful training situations, identifying which soldiers remain more balanced, so they can be picked for the harder missions.
