🧩 词语组成解析
radioactivity
[,redɪoæk'tɪvəti]
n. 放射（性）;辐射能;
radio光线+act行动，做+ivity表示情况、状态、“...性”、“...力” →放射性；[核] 放射能力；[核] 放射现象
unit
['ju:nit]
n. 单位，单元;装置;个体;[数]单位数;
🗣️ 情景例句
so it's my pleasure
所以现在我很乐意
They fought for the sake of their country.
他们为国而战。
No, she isn't wearing a sweater. She's wearing a white blouse.
没穿。她穿了一件白色的衬衫？