为什么How much are they?用are,而How much do they cost?就用do呢?

为什么How much are they?用are,而How much do they cost?就用do呢? A how much cost they are B how much do they cost C how much How much do they cost? How much do they cost对还是how much are the cost对 How much are they? how much are they how much ( ) are they how much are they ,how much they are How much are the pants?They”re50dollars 为什么这里要用they are how much ( ) are they they ( )40yuan How much are these 和how much are that 都是用they how much do the glasses cost?回答“it cost”还是“they cost”