[单项选择]What is the writer's main purpose in writing this text A. to give her opinion of the holiday village B. to describe what her family did at the holiday village C. to give advice to a friend going to the holiday village D. to complain about the holiday village
第19题: [单项选择]What is the purpose of pressure-vacuum relief valves? () A. Regulation of discharge pressure from cargo pumps B. Maintaining constant velocity in cargo lines C. Regulation of suction head on cargo pumps D. To maintain a tank or void at atmospheric pressure 参考答案:D