题目

When I was in my third year at university, my roommates were American footballers, so I decided to join them. I remember seeing them in front of me wearing pads (防护垫), and thinking they were going to kill me. I got tackled (阻截) so hard that I was frightened. But then I realized it was just physical contact. I’ve been addicted since.The fundamental aim of the game is to score by running with the ball into, or receiving the ball inside the opposition’s end zone. Every player on the field has a set responsibility. I’m a running back. My job is using my speed, strength and skill to4．用已知物质的量浓度的盐酸滴定未知物质的量浓度的NaOH溶液时，下列操作中不正确的是（　　）A．酸式滴定管用蒸馏水洗净后，直接加入已知物质的量浓度的盐酸B．锥形瓶用蒸馏水洗净后，直接加入一定体积的未知物质的量浓度的NaOH溶液C．滴定时，应左手控制活塞，右手摇动锥形瓶，眼睛时刻注视着锥形瓶内颜色的变化D．读数时，视线与滴定管内液体的凹液面最低处保持一致