perturbs

"You must do your homework before you can watch television."

"The student's ability to concentrate in noisy environments was crucial for success in the class. "

"The coffee concentrate was strong, so a little went a long way. "

"The loud music caused a disturbance in the library, making it hard to concentrate. "

"The unexpected announcement of a new school policy unsettled many parents. "

"The marine biologist studied the asteroid's five arms carefully. "

"the flutter of a fan"

"The calculation of how much flour to buy for the cookies involved adding up the recipe's ingredients. "

"He was slightly built, but tall."

"The gravitational pull of the Earth keeps us on the ground. "

"We need to bring the balance of power into equation"

"The student was exerting all her effort to finish the difficult exam. "