Triangular number
三角形数
🧩 词语组成解析
🗣️ 情景例句
I believe stamp collecting is an interesting hobby.
我认为收集邮票是一种有趣的爱好。
Lend your money and lose your friend.
赔了夫人又折兵。
It was noticed that there were no signs or warnings on the supply lines that ran round the port.
人们这才注意到，铺设在码头周围的供应管道上没有贴标签或告示。