Briefly describe the mode of transportation and the advantages and disadvantages of various modes of transportation.

1) River-sea transportation: also called waterway transportation, including river transportation and sea transportation. Its advantages are large volume and low freight. Its disadvantages are the slowest speed, unstable sailing schedule, great influence by climate and environment, and great risk. 2) Railway transportation: it is a kind of land transportation. Its advantages are high transportation speed, strong transportation capacity, low cost, punctuality and almost no influence from weather and environment. Its disadvantages are large investment and long railway construction period. 3) Automobile transportation, also called road transportation, constitutes the main force of land transportation together with railway transportation. Its advantages are great flexibility, strong adaptability, high speed and door-to-door. Its disadvantages are small traffic flow, high energy consumption and high transportation cost. 4) Air transportation: also called air transportation. Its advantages are the fastest speed and strong flexibility. Its disadvantages are the highest transportation cost, the smallest volume and high requirements for goods, such as dangerous goods, and the air transportation of long, ultra-high and overweight goods is more troublesome. 5) Postal transportation: also known as mail transportation, it is a way to send goods through the post office. Its advantages are wide network coverage and low cost. 6) Other transportation: pipeline transportation is common. Its transportation capacity is large, continuous, fast, stable, safe and reliable, and the freight rate is low. After the one-time investment of the pipeline is completed, automatic control can be realized and the maintenance cost is low.