阅读以下说明和C++代码，填补代码中的空缺，将解答填入答题纸的对应栏内。
[说明]
在股票交易中，股票代理根据客户发出的股票操作指示进行股票的买卖操作。其类图如下图所示，相应的C++代码附后。
类图
[C++代码]
#include＜iostream＞
#include＜string＞
#include＜vector＞
using namespace
std;
class Stock {
private:
string name;
int quantity;
public:
Stock(string
name,int quantity) {this-＞name=name;
this-＞quantity
=quantity;}
void buy() {cout＜＜"[买进]股票名称:"＜＜name＜＜",数量:"＜＜quantity＜＜
endl;}
void sell() {cout＜＜"[卖出]股票名称:"＜＜name＜＜",数量:"＜＜quantity
＜＜endl;}
};
clasS order{
public:
virtual void
execute()=0;
};
class
BuyStock:______ {
private:
Stock* stock;
public:
BuyStock(Stock*
stock){______ =stock; }
void execute(){
stock一＞buy();
}
};
//类SellStock的实现与BuyStock类似,此处略
class Broker{
private:
vector＜Order*＞ orderList;
public:
void
takeOrder(______ order)( orderLiSt.push back(order);}
void placeorders()
{
for(int i=0;i＜orderList.Size(); i++){______ -＞execute();}
0rderLiSt.clear();
}
};
class
StockCommand{
public:
VOid main(){
Stock* aStock=new
Stock("股票A",10);
Stock*bStock=new
Stock("股票B",20);
Order*buyStockOrder=new BuyStock(aStock);
Order*
sellStockOrder=new SellStock(bStock);
Broker* broker=new
Broker();
broker-＞takeOrder(buyStockorder);
broker-＞takeOrder(sellStockOrder);
broker-＞ ______ ();
}
};
int main(){
StockCommand*
stockCommand=new StockCommand();
StockCommand-＞main();
delete
StoCkCommand;
}
