Paul finished his homework first. Then he had a bath. 用过去完成时

Paul finished his homework first. Then he had a bath. 用过去完成时 I waited until he had finished his homework.请问这句的过去完成时为何是用在f a homework he his finished first连词成句 he went home ( ) he had finished his homework.A.when B.while He had finished his homework before he watched TV With his homework he went home happily A finished B had fini He had finished his homework already.(改为否定句) I __ he had finished his homework at this time he finished his homework _____. He___until he finished his homework? 1.He finished his homework,then he went on _______a letter. Jim finished his homework and then he went back home.(改同义句)