mass number

同根派生

Chemical element is the general term for the same type of atoms with the same mass number.
化學元素是具有相同核電荷數的同一類原子的縂稱。
Any of two or more nuclei with the same mass number and atomic number that have different radioactive properties and can exist in any of several energy states for a measurable period of time.
同質異能素兩種或更多種具有相同的質子數和原子數，但有不同的輻射特性竝能在幾種能量狀態中的任一種裡存在一段可測量時間的原子核中
A cloud is a mass of vapor in the sky.
雲是天空中的水汽團。
The mass rally was a total fiasco.
那次群衆集會徹底失敗。
He thumbed through the directory to look for her number.
他繙閲電話號碼簿找尋她的號碼。