AA? And of course, the answer is technetium. Terrific.

AA队的答案是？当然答案是锝。漂亮。

But it left behind a slurry of other elements, including types of radioactive strontium, caesium, and technetium.

但它留下了其他元素，包括放射性锶、铯和锝。

As a result technetium, element number 43, and promethium, 61, are always radioactive (and are not found naturally in detectable quantities).

锝（43号元素）和钷（61号元素）都是放射性的，并且在自然中的存在数量无法侦测。