Trackballs
(trackball 的复数) n. 追踪球；轨迹球
🗣️ 情景例句
Hmm?
嗯？
It's a beautiful country with several chains of mountains.
这个国家很美，它有很多山脉。
The party then searched the whole cave thoroughly but did not find anything except an empty tin trunk.
队员们接着又把整个洞彻底搜寻了一遍，但除了一只空铁皮箱外什么也没找到。