题目

有一反应：2A+B2C，其中A、B、C均为气体，下图中的曲线是该反应在不同温度下的平衡曲线，x轴表示温度，y轴表示B的转化率，图中有a、b、c三点，如图所示，则下列描述正确的是      A．该反应是放热反应  B．b点时混合气体的平均摩尔质量不再变化 C．T1温度下a点表示若想达到平衡，可以采取增大压强的方法 D．c点可表示v(正)＜v(逆)阅读短文，选择正确答案。 My Class 　　There are forty-eight students in our class. There are twenty-three boys and twenty-five girls. Some students live near the school, and some live far from（远离）the school. 　　In front of my classroom, there is a big tree. Near the tree you can see a garage. Our teacher's car is in it now. Our school is very beautiful. We like our school. （1）There are ________ students in our class. [　　] A．forty B．twenty-three C．forty-eight （2）All the students like [　　] A．the big tree B．the garage C．their school （3）A garage is ________ the tree. [　　] A．near B．behind C．in front of （4）A big tree is ________ the classroom. [　　] A．behind B．in the front of C．in front of （5）Our school is ________. [　　] A．beautiful B．big C．small