1. Radioactivity is the ejection of particles or radiation from the nucleus. 放射性是原子从核中射出粒子或辐射的现象。
2. This photo records the amazing beauty of dust particles floating in the sunlight. 这张照片记录了在阳光中漂浮的尘埃微粒的惊人的美。
3. Some of these particles are stable and form the normal matter, the others live for fractions of a second and then decay to the stable ones. 这些粒子中的一部分是稳定的并且构成了普通物质,其它的只存在一秒钟的几分之一,然后衰变为稳定粒子。