the lights are on but nobody’s home
US /ðə laɪts ɑr ɑn bʌt ˈnoʊbədiz hoʊm/
UK /ðə laɪts ɑr ɑn bʌt ˈnoʊbədiz hoʊm/

1.
灯亮着但家里没人, 不聪明, 心不在焉
used to describe someone who is not very intelligent or is not paying attention
:
•
He just stared blankly when I asked him a question, like the lights are on but nobody’s home.
我问他问题时,他只是茫然地盯着,就像灯亮着但家里没人一样。
•
Sometimes I worry about my brother; he can be a bit slow, you know, the lights are on but nobody’s home.
有时我担心我的兄弟;他可能有点迟钝,你知道,就是那种灯亮着但家里没人的情况。