题目

―Hello, is that Ms. Blackburn, the headteacher speaking? ―I'm sorry. There isn't ____ Ms. Blackburn in our school. A. the                B. a               C. one                D. 不填 答案：B如图是某种物质熔化时温度随时间变化的图象，第10min到第25min物质处于________态，该物质的凝固点是________℃．