java题求助

还望那位高手能帮忙做做。定有重谢！不懂者勿打扰！谢谢！
abstract class PhoneCard
{
double balace;
___(1)___ performDial();
double getBalance()
{ return balance; }
double TimeLeft()
{
double current=balance;
int times=0;
do
• {
___(2)___
times++;
}while(balance>=0);
balance=current;
return times-1;
}
}
abstract class Number_PhoneCard extends PhoneCard
{
long cardNumber;
int password;
String connectNumber;
Boolean connected;
Boolean performConnection( long cn, int pw )
{
if( cn==cardNumber && ___(3)___ )
{
connected=true;
return true;
}
else return false;
}
}
class IC_Card ___(4)___
{
boolean performDial()
{
if(balance>0.9)
{
balance-=0.9;
return true;
}
else return false;
}
}

1.abstract Boolean
2.balance --;
3.pw == password
4.extends PhoneCard
5.balance -= (0.5+additoryFee);

1:boolean
2:current--
3:pw==password
4:extends PhoneCard
5:balance-=0.5+additoryFee

1. abstract boolean
2. balance--;
3. pw==password
4. extends Number_PhoneCard
5: balance-=0.5+additoryFee;

abstract class PhoneCard
{
double balance;
abstract boolean performDial();
double getBalance()
{ return balance; }
double TimeLeft()
{
double current=balance;
int times=0;
do
{ balance--;
times++;
}while(balance>=0);
balance=current;
return times-1;
}
}
abstract class Number_PhoneCard extends PhoneCard
{
long cardNumber;
int password;
String connectNumber;
Boolean connected;
Boolean performConnection( long cn, int pw )
{
if( cn==cardNumber && pw==password )