undermines

"My friend told me there was something in the box, but I didn't know what it was yet. "

"The constant noise from the construction site made it hard to concentrate on my homework. "

"The underneath of the aircraft was painted blue."

"The student's sabotage of the rival team's project was successful, delaying their presentation and causing them to lose the competition. "

"The student studied hard with the purposes of getting good grades and graduating on time. "

"Joe was always complaining about the noise made by his neighbours."

"They bickered about dinner every evening."

"The student undermined the sandcastle by digging a tunnel beneath it. "

"The storm was incredibly destructive, tearing down trees and damaging many homes. "

"He spent six years in the military."

"She struggled to play the difficult passages."

"The foundation of his institute has been wrought with difficulty."