corrugate

"The train tracks are two parallel lines that run through the entire town. "

"It is difficult to provide for my family working on minimum wage."

"It requires great strength to lift heavy objects."

"It is hard work to swim against the current."

"She crumpled the paper in her hand after realizing she had made a mistake. "

"Be careful not to wrinkle your dress before we arrive."

"Cart wheels can furrow roads."

"The children squinted to frighten each other."

"The new computer keyboard has small grooves to help your fingers find the correct keys. "

"The old map showed many wrinkles on its paper surface. "

"Her brow corrugated with concern as she read the difficult math problem. "

"The teacher pointed to the student's forehead and said, "Concentrate!" "