单项选择题
Persons who load and discharge ships are called （）(装卸工人).
A. cargo workers B. dockers C. port men D. stevedores
单项选择题 There is no power for the （）(起货机).
单项选择题 Containers are loaded and discharged by （）(龙门吊).
单项选择题 Our heavy derrick has been （）(不用)for a long time.
