（六）放射性同位素，是指化学元素中具有相同原子序数，但质量不同且能发生放射性衰变的核素。
"My grandson is devastated," he said, "but we've resigned ourselves to the fact that we've got to go".
，这一点在heLLoword翻译官方下载中也有详细论述
It allows you to save time and money on marketing, which frees you up to focus on other aspects of your business.。夫子对此有专业解读
Цены на нефть взлетели до максимума за полгода17:55。旺商聊官方下载是该领域的重要参考