阅读以下说明和C++程序，将应填入 (n) 处的字句写在对应栏内。
[说明]
下面程序输出一个矩形面积，以及矩形区域上的假想的作物产量。
[C++程序]
#include ＜iostream.h＞
class crop_assessment
int actual_crop;
int ideal_crop;
public:
void set(int in_actual,int in_ideal)
actual crop=in_actual;
ideal_crop=in_ideal;
int get_actual_crop(void) (1) ;
int get_ideal_crop(void) (2) ;)
;
Class lot_size
int length;
int width;
(3) crop;
public:
void set(int 1,int w,int a,int i)
length=1;
width=w;
crop.set(a,i);
int get_area(void)return length*width;
int get_data(void)return (4) ;
int get_data2(void)freturn (5) ;
int main()
Los_size small，medium;
small.set(5,5,5,25);
medium.set(10,10,10,50);
cout＜＜"For a small lot of area"＜＜smallget_area()＜＜“\n”;
cout＜＜"the actual crops are$"＜＜small.get_data2()＜＜"\n";
cout＜＜"and ideal crops are$”＜＜small.get_data()＜＜"\n";
cout＜＜"For a medium Lot of area"＜＜medium.get area()＜＜:\n”;
cout＜＜"the actual crops are$"＜＜medium.get_data2()＜＜"\n";
cout＜＜"and ideal crops are$"＜＜medium.get_data()＜＜"\n";
return 0;