单项选择题
The main （）(保护层) is paint.
A. primer boat B. protective coat C. top coat D. under coat
单项选择题 The purpose of lookout is to prove the （）(安全) of a ship.
单项选择题 Where is the （）(撬棍)？
单项选择题 please use the （）(拖把) to clean the floor.
