两电阻R1=10Ω、R2=20Ω，R1最大允许电流为200mA，R2最大允许电流

在C++中，用于实现运行时多态性的是

A．内联函数

B．重载函数

C．模板函数

D．虚函数

新生儿乳腺增大多在生后( )。

A．1～2天出现
B．5～7天出现
C．3～5天出现
D．4～6天出现
E．9～12天出现

无论是看涨期权还是看跌期权，在期权标的物的市场价格波动时，期权的内在价值都大于零或等于零，不可能为负值。( )

Horse thieves, cattle rustlers, bank robbers, train and stagecoach robbers, highwaymen, murderers, these were but some of the criminals who infested the American frontier during the 19th century. In English legend Robin Hood can be considered a bandit, but the outlaws of the Old West were far more violent men and women without any scruples when it came to taking property or life.
The careers of many outlaws have been glamorized through fictional accounts of their deeds and their exploits have been the basis for many movie scripts.
The era of the American outlaw lasted about 100 years roughly from 1800 to 1900．There had been lawlessness during the Colonial Era. Frontiers have always attracted misfits, failures and renegades who hope to profit by being beyond the reach of government. In the years just before the Revolutionary War, gangs of horse thieves in the back country of South Carolina were broken up by organized bands of farmers called regulators.
As frontier settlement expanded rapidly after the Revolution, more opportunities for criminals opened, two common types of bandits were highwaymen and river pirates. Highwaymen accosted people who traveled on foot or horseback, while river pirates preyed upon the boat traffic on the Ohio, Mississippi, and other rivers. Some bandits engaged in both.
Criminals in the West gathered momentum with the gold rushes to California, Idaho, Montana, Nevada, and other states. Stagecoaches and trains carrying gold and money became prime targets for bands of outlaws. Bank robberies emerged after the California Gold Rush of 1849 and as prosperity found its way to frontier towns. The first stage robbery was recorded in 1851, and the first train robbery happened in 1866.
After the Civil War there was the growth of the cattle kingdom in Texas and neighboring states. Cattle rustling and horse theft turned into significant operations. Range wars bred a great amount of violence. Cattlemen fought over land and water rights, and they fought with great bitterness against sheep farmers. In Texas, range wars were fought over the use of barbed wire to fence grazing land.
By the end of the 19th century, the frontier era was past. Major crime shifted to the cities. Ethnic gangs had existed in the slums for decades, preying mostly on their fellow immigrants. With the arrival of Prohibition in the 1920s, an impetus was given to the formation of organized crime as it exists today.

Modern crime is characterized by
[A] unlimited violence
[B] great diversity
[C] unimaginable cruelty
[D] careful planning

下面不属于保安单元基本功能的是（）。

A、防止外线上的过电压

B、把交换机的语音信号送到外线

C、防止过电流对设备的伤害

D、防止过电流对人身的伤害