Chinese by more and more people from all over the world today.
A:learn
B:learned
C:is learned
D:was learned
如图是某人在1个标准大气压下的一次平静呼吸中肺内气压的变化曲线.在AB段有关肌肉的舒缩状态是( )
32-17=____
54-25=____
70-37=____