阿斯匹林的主要成分是乙酰水杨酸（化学式为C3H2O4），具有抑制血小板发挥作用的功能，是治疗心血管疾病的重要药物之一．
（1）乙酰水杨酸中氢、氧两种元素的质量比为
（2）乙酰水杨酸具有酸性，若在其无色溶液中滴入紫色石蕊试液，观察到溶液呈 色．
（3）人体内的血小板有何作用？ 。
（1）1：32；（2）红；（3）加速血液凝固．
题目分析：（1）乙酰水杨酸中氢、氧两种元素的质量比为（1×2）：（16×4）=1：32．
（2）紫色石蕊溶液遇酸性溶液变红，遇碱性溶液变蓝；由题意，乙酰水杨酸具有酸性，若在其无色溶液中滴入紫色石蕊试液，溶液呈红色．
（3）血小板能够堵塞伤口，其中还含有促进血液凝固的物质，起止血和加速凝血的作用．
点评：本题难度不大，掌握有关化学式的计算、酸的化学性质、人体内的血小板的作用等是正确解答本题的关键．
根据对话内容，从下面方框中选择适当的短语填空，使对话内容完整正确。
Life is not easy, so I’d like to say “When anything happens, believe in yourself!”. When I was a young boy, I was 小题1: speak to anyone. My classmates often 小题2: me. I was sad but could do nothing. Later, something happened, and it changed my life. It was an English speech contest. My mother asked me to take part in it. What a terrible idea! “Come on, boy. Believe in yourself! You are 小题3: to win.” Then mother and I talked about many different topics. At last, I chose the topic “Believe in yourself”. I 小题4: to remember all the speech and practised it over 100 times. With my mother’s great love, I did well in the contest. I 小题5: believe my ears when the news came that I had won the first place. I heard the cheers from the teachers and students. |