A:①②
B:①②③
C:①②④
D:①②③④
Dale used to _____to office in his car, but he is used to_____ the bus now.
如图表示某绿色植物的非绿色器官在氧浓度为a、b、c、d时,CO2和释放量和O2吸收量的变化。下列相关叙述正确的是()
— No, they aren't. They are .