【单选题】A( n) _____ is a tax on imports that is stipulated as a money amount per unit . a. specific tariff b. ad valorem tariff c. effective tariff d. optimal tariff
【简答题】看图完成答句,一空一词。 1. Where are the boys? They are ________ the ________. 2. What are one group of the boys doing? They are _________________________. 3. What are the other group of boys doing? They are ___...