VOA慢速英语:Switzerland Opens World’s Longest, Deepest Rail Tunnel

tunnel – n. a passage that goes under the ground, through a hill, etc.

cargo – n. something that is carried from one place to another by boat, airplane, etc.

commercial – adj. related to or used in the buying and selling of goods and services; concerned with earning money

freight – adj. goods that are carried by ships, trains, trucks or airplanes