There was a slackening of western output during the 1930s.
20 世纪 30 年代西部的产出有所减少。
2V-ERG (使)松开;(使)放松 If your grip or a part of your body slackens or if you slacken your grip, it becomes looser or more relaxed. (使)松开;(使)放松 [Also VERB n]
Her grip slackened on Arnold's arm. [VERB]
她紧握着阿诺德的手松开了。
Muscles stretch, slacken and relax during childbirth.