“本年利润”账户的特点是，在年度中间该账户有余额，余额可能在借方也可能在贷方。年终结算时，要将本账户余额转入“利润分配”账户，年末结转后，该账户无余额。( )

By the time he realizes he _____ into a trap, it'll be late for him to do anything about it．

A．walks

B．walked

C．has walked

D．had walked