单选题 All passengers are advised that the seat belts should be tightly fastened ______ takeoff and landing.

【正确答案】 A

【答案解析】[解析] 词汇：介词
1．这是一道词汇题，选项均为介词。
2．原文意思是“起飞和着陆前要系好安全带”，由此可见A．prior to为正确选项。