这里为什么要用ing形式呢?

working现在分词作定语.动词原形是不能作定语的.
transport= a means of transportation
transport 用于交通的某个东西 ,transportation 交通工具的统称
再问： 那 what kind of transport do you have what kind of transportation do you have 哪个是对的?
再答： what kind of transportation do you have？