I know this topic is something old, but i had a similar problem. I want only one item in cart and if customer adds a new one, i want to replace the old one with the new one. So i override the addAction (described here like this:

public function addAction(){
    $items = $this-&gt;_getCart()-&gt;getItems();
            foreach ($items as $item)
                    {
                            $itemId = $item-&gt;getItemId();
                            $this-&gt;_getCart()-&gt;removeItem($itemId);
                    }
    parent::addAction();


}

How to allow only one product in a cart?
I was watching a video linked in this answer and it made the following claim:


  [...] like most words in English is derived from German.


That got me thinking. While I know that Germanic languages have greatly influenced English, so have the Latin and Celtic ones (and various others to a greater or lesser degree). Is it true that more than 50% of the English vocabulary is derived from Germanic roots?

More generally, can someone point me to data on this? I imagine attempts have been made to quantify the contribution of different languages to English; what were the results? What percentage of the language comes from each source?

Ideally I would like to see this expressed in terms of % of words but I am aware that, at least to some linguists, attempting to quantify vocabulary is anathema (to give a simple reason, all languages that allow number construction have an infinite  vocabulary by definition), so alternative approaches to quantifying this are also welcome.
