第2题: [单项选择]In a crossing situation,the stand-on vessel should normally(). A. take action to cross ahead of the other vessel B. take action to pass astern of the other vessel C. maintain course and speed D. change course and increase speed 参考答案:C
第3题: [单项选择]某溶液的pH值约为6,用酸度计测定其精密pH时,应选择的两个标准缓冲液的pH值是 A. 1.68,4.00 B. 5.00,6.86 C. 4.00,6.68 D. 6.86,9.18 E. 1.68,6.86 参考答案:C 答案解析:选择两种pH值约相差3个pH单位的标准缓冲液,并使供试液的pH值处于二者之间。