下面是摘自这张卡的term and conditon 的fine print，也请各位高人看看是不是那么回事儿，还是俄理解错了

Your account's Variable Rate Index for any billing cycle will be chosen by us from among the Prime Rates published in The Wall Street Journal's "Money Rates" section during the three (3) months prior to the month which contains that cycle's Billing Cycle Closing Date, but will not be less than 5.00%. Your account rate for Purchases and Balance Transfers will be your account's Variable Rate Index plus a Purchase Margin of 10.99%, but a rate of 0.00% will apply to each purchase during the billing cycle in which the purchase is made and the three subsequent billing cycles so long as you make all minimum payments on time, do not exceed your credit limit, and keep your account otherwise in good standing. If you default on the account we will assess the seriousness of the default and may impose a higher rate, such as the standard purchase rate or the default rate, to existing balances and/or new transactions. Your account rate for cash transactions will be the Variable Rate Index plus a Cash Advance Margin of 14.99%, 19.99% or 24.99% based on our assessment of your credit history and creditworthiness. Finance charges on balance transfers and cash advances begin to accrue on the date we process the transaction. Any rate applicable to any component of your account, including any Default rate, will be applied throughout the entire billing cycle which contains the effective date of that rate, and will apply to previous balances as well as new transactions and charges.