Hvt
半值厚度辐射屏蔽
🗣️ 情景例句
A couple of weeks.
两、三个星期吧。
Today English is the international language of business and trade.
如今英语是商务和贸易的国际性语言。
One of links in the chain that drives the wheels had snapped.
驱动轮子的链条断了一节。