Then the back charged you a S20 fee for overdrawing your account.
银行就因为你在帐户上透支，收了你20美元的费用。
2
You may not even know if this is happening; your bank will not notify you when you make your purchase that you are overdrawing your account.
你可能甚至不知道，如果这种情况发生；你的银行不会通知你，当你使你购买你透支你的账户。
3
Clients' transactions will be stopped only in the circumstance of serious overdrawing of the accounts, that is to say, transactions at this type of account have strict restrictions.