堆在桌子上) 。Pile up 作不及物动词用, 意为”积压; (若干汽车) 相撞”：1) Perishable goods are piling up at the docks. (码头上易腐烂的货物堆积如山。) 2) Several cars piled up after ignoring the fog warning on the motorway. (由于无视高速公路上的大雾警告, 有好几辆汽车相撞。)题目7：The workmen made so much _____ that Mrs. Walker had to spend three days cleaning up afterwards.