题目

   Most people today think of chocolate as something sweet to eat or drink and can be easily found in stores around the world. It might surprise you that chocolate was once highly treasured.    The wealthy people of Spain first enjoyed a sweetened chocolate drink. Later, the popularity of the drink spread throughout Europe. Chocolate remained a drink that only wealthy people could afford to drink until the eighteenth century. During the period known as the Industrial Revolution, new technologies helped make chocolate less costly to produce.    Farmers grow cacao trees in many co将如图所示的长方体，从中间切开变成完全相同的两块，并将一块按照图中所示放在另一块的上面．若长方体放在水平桌面上，则长方体对桌面的前、后两次压强之比P1：P2为（　　）A．1：1B．1：4C．2：1D．1：2