通常来说，新飞机的产品周期一般为20年左右，但也并非总是如此。

Normally, new aircraft have a product life of around 20 years. But not always.

youdao

一般而言，项目生命周期包括在一个或多个产品生命周期之内。

Generally, a Project Life Cycle is contained within one or more Product Life Cycles.

youdao

是了，它有周期性，犹如一个女人一般。

Yeah, it is periodic, again, just like a woman.

youdao

是了，它有周期性，犹如一个女人一般。

Yeah, it is periodic, again, just like a woman.

youdao