falling-off
noun/ˌfɔːlɪŋ ˈɒf/
/ˌfɔːlɪŋ ˈɔːf/
(British English) (also more frequent fall-off British and North American English)
[singular]- falling-off (in something) a reduction in the number, amount or quality of something
（数量的）减少；（质量的）降低