Decay series
[化] 衰变系; 放射系
🧩 词语组成解析
🗣️ 情景例句
Is it all right if I use my credit card?
如果我使用信用卡行吗？
The president must have the approval of Congress to declare war.
总统若要宣战，必须获得国会的承认。
I sat in the front of the bus to get a good view of the countryside.
我坐在汽车的前部，以便饱览农村风光。