题干
— The _____ of July is your birthday. What do you usually do?
— I usually help my mother with some housework because I want her to have a rest _____ that day.
A：first; on
B：one; on
C：first; in
D：one; in
答案(点此获取答案解析）
A
Z(g)＋M(g)＋N(s)进行过程中X的转化率随时间变化的关系。若要改变起始条件，使反应过程按b曲线进行，可采取的措施是( )