1.When to meet senesce?

1.什么时候会开始衰老？

2.Chillness intensified the senesce of leaves, enhanced the MDA content and the O2-. produce rate, this was more evident in Shanyou63.

2.低温处理加剧了叶片的衰老，使得MDA含O2-升，两优培九的升幅较汕优63小。

3.But hang on -- how do we know that radioactive atoms don't senesce?

3.但是，听清楚了—我们怎么知道放射性原子不衰老？