Stacks
n. 堆叠；进程堆栈应用；书库（stack的复数）
🗣️ 情景例句
What classes are mandatory for your major?
你的专业什么课是必修的？
John and I are old friends.
我和约翰是老朋友了。
It's a very old castle. It is the oldest one in Britain.
这个城堡很古老，它是英国最老的了。