虛擬貨幣該存放在哪裡？
Although bitcoin is a virtual currency, it still needs to be put in an actual safe box.
雖然比特幣是虛擬貨幣，但還是需要存放於實體的保險箱中。
virtual(adj.)虛擬的currency(n.)貨幣actual(adj.)真實的、現實的
There are no actual Bitcoins locked in it, but a private key.
保險箱內不是存放「實體比特幣」，而是存放私人鑰匙。
actual(adj.)真實的、現實的lock(v.)保管、上鎖
This private key is used and combined with a public key so that you can access your bitcoins.
需要用私人鑰匙與公共鑰匙結合後，才可釋放比特幣使用。
combine(v.)結合access(v.)取得
如同紙鈔或黃金，比特幣的私人鑰匙一旦被偷，便難以挽回。
Just like cash or gold, when the private key to your bitcoins is stolen, it is hard to get it back.
在2013 年，有個比特幣用戶沒有備份私人鑰匙，所以當他不小心搞丟了硬碟，竟然損失了 7500 BTC 的比特幣。不過這些錢沒人可以花的了半毛，因為丟失的比特幣會就此永遠人間蒸發。
backup(v.)備份accidentally(adv.)意外地remain(v.)保留、仍是
In 2013, there was a Bitcoin user that didn’t backup his private key. So when he accidentally lost his hard drive, he lost his 7,500 bitcoins, which no one is able to spend since lost Bitcoins remain lost.
比特幣錢包的供應商 Xapo，有一座「保險箱」就位於瑞士琉森湖的東部山脈裡。
locate(v.)位在⋯⋯
Xapo, a company that provides bitcoin wallets, has a safe box located in the east mountains of Lake Lucerne in Switzerland.
那裡原本是瑞士軍方的堡壘。
location(n.)位置fort(n.)堡壘army(n.)軍隊
The location used to be a fort for the Swiss army.
這個保險箱不僅可承受原子彈的爆炸，還有可以抵禦電磁脈衝EMP攻擊的冷卻室。
vault(n.)保險庫withstand(v.)承受atomic(adj.)原子的protect(v.)保護attack(n.)攻擊
This safety vault can not only withstand an atomic bomb, but it is also in a cold storage that protects it from EMP attacks.
資料庫內沒有網路對外連接，即便「線下」簽單，也還需全球另外 2 點核准。
transaction(n.)交易offline(adj.)離線的approve(v.)同意
The system is not connected to the internet which means when you go through the signing process of the transactions offline, it must be approved at two other places in the world.
所以雖然存放的貨幣是虛擬的，但他的保全可是一點都不虛擬。
currency(n.)貨幣virtual(adj.)虛擬的nevertheless(adv.)儘管如此