请教,it was barking _ ___let him in 答案选 for someone to 我选得是so that someone

so that表目的如果要用so that的话应该说it was barking so that someone would let him in.如果按照你说的那么就时态混乱了.would 在这里是做什么解释？会？愿意？就是will的过去式。