上个世纪，人类的平均寿命稳步增长。

The average human ___life ___span has increased steadily over the last century.

一些电子产品的寿命很短。

Some electrical products have a short ___life ___span.

随着寿命的增加，子女照顾年迈父母变得越来越普遍。

Now that the ___life ___span has increased, it is more common for children to care for their elderly parents.