I am as old again as you.

(误译)我又像你那样老了。
(正译)我的年纪比你大一倍。

as old again as 年纪比……大一倍

My aunt is as old again as I am.
我姑姑的年龄是我的二倍。

My uncle is as old again as I am.
我叔叔的年龄比我大一倍。

大一倍：

需要一个比这里大一倍的地方。
We need a place twice larger than this one.

它们好像比通常的（花朵）大一倍。
They're almost twice as large as usual.

我们需要一个比这里更大一倍的地方。
We need a place(which is) twice larger than this one.

……是……两倍：

In the year to July the price of oil almost doubled.
到今年七月底石油价格几乎增至两倍。

My husband has an office that doubles as a spare bedroom.
我丈夫有一间比单人卧房大两倍的办公室。

as...as 像……一样，同……一样

As young as your hope. as old as your despair.
如你的希望般年轻，如你的绝望般苍老。

Wet as the spring. Hot as the summer. Gale as the autumn.
潮湿得像春天。热得像夏天。大风得像秋天。

I would imagine you are a man of honor, as well. As am I.
我也想象得出，你跟我一样，是一位很讲信义的正派人。