"idle, meaningless talk," 1918, probably echoic; the adjective meaning "bland, dull" is from 1919, perhaps influenced by French blasé "bored, indifferent." The blahs "depression" is attested by 1966.
雙語例句
1. How can you build socialism if you just blah - blah and don't do a stroke of work?
成天磨嘴皮子不干活,還能建設好社會主義?
來自《現代漢英綜合大詞典》
2. There he goes , blahblahblah, talking nonsense as usual.