Path shrink parts sizes shrink, open and close the required power is reduced, at the same timeexpand the scope of application components.
通径收缩能使零件尺寸缩小，开、闭所需力相应减小，同时可扩大零部件的应用范围。
2
Houses built before 1939 use about 50% more energy per square foot than those built after 2000, mainly due to the tiny cracks and gaps that expand over time and let in more outside air.