How long has Lidai Diwang Miao been in part of a middle school in Beijing

A．Understanding of a language.
B．Ability to speak a language.
C．Obvious differences between languages.
D．The different idiomatic expressions between languages.

A．They want to increase the general ability of our bodies.
B．They may be able to find a better way to our life.
C．If they can pin down the biochemical process that makes us age, there will be hope for extending the length of life.
D．They want to find out if there is a link between how efficiently a cell could repair itself and how long a creature lives.