若ad=bc，则下列各式中不正确的是（ ）
A：ac=bd
B：db=ac
C：dc=ba
D：ab=cd
— 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.
当光合速率等于呼吸速率时,假设叶绿体产生的ATP量为a，线粒体和细胞质基质产生的ATP量为b。则两者之间的关系为（ ）
下列最能说明生产关系必须适应生产力发展原理的是( )
I sit on the chair and talk my mother.
下图曲线为中国民族资本主义在曲折中发展，图中B处所占比例较高的主要原因是（ ）
