【单选题】某温度下,在容积固定不变的密闭容器中发生下列可逆反应:X(g) + 2Y(g) 2Z(g)。 平衡时,X、Y、Z的物质的量分别为1 mol、1 mol、2 mol,保持温度不变,再向容器中分别充入1 mol、1 mol、2 mol的X、Y、Z,则下列叙述中正确的是
A.
刚充入时,反应速率V (正)减小,V (逆)增大
B.
达到新平衡时,容器内气体的平均相对分子质量增大
D.
达到新平衡时,容器内气体的百分组成和原来相同
【单选题】I’ve got to go now. Something has just _________ at school and I’m needed there.
【单选题】---Do you still go to school in your mother’s car? ---No, since I started secondary school, I’ve come to school by bike ______.