関連ワード:  why is it economic to carry out transport by waterways    why is it economic to carry out transport by waterways std 6    why is it economic to carry out transport by waterways answer    why is it economic to carry out transport by waterways short    why is it economic to carry out transport by waterways answer in short    why is it economic to carry out transport by water waves    why is water transport cheaper than other means of transport    why is water transport cheaper than other transport    why are waterways the cheapest mode of transport  
結果 : why is it economic to carry out transport by waterways