Spiroannulation
[化] 螺增环
🗣️ 情景例句
He never speaks unless he is spoken to.
除非别人先对他开口，他从不先开口。
When the phone rang, I was painting upstairs.
当电话铃响的时候，我在楼上画画。
When was the house built?
这幢房子是什么时候建造的？