As part of a delicately balanced system, the human heart secretes a hormone, a substance that controls the amount of salt in the blood and the volume of blood circulating within the body. Only very small quantities of the hormone are required. This hormone is extremely important in regulating blood pressure and is found in large amounts in the blood of those suffering a heart attack.
If the statements above are true, then it must also be true that

A．if there is a deficiency in the amount of heart hormone secreted, low blood pressure will result.

B．it is large quantities of the heart hormone that cause heart attacks to occur.

C．the effects of a small amount of the heart hormone will be long-lasting in the body.

D．if a device that is only a mechanical pump is used as an artificial heart, it will not perform all the functions of the human heart.

E．(E) any drug that regulates blood pressure will have its effect by influencing the amount of the heart hormone secreted.

图15为某月某日气压（单位百帕）形势分布图，联系所学回答问题：

（1）说明该日内蒙古河套平原的天气状况。

（2）据图，指出该日我国大陆沿海航线中，航运安全隐患较大的航段，并简析原因。

（3）比较丙、丁两地风力的大小，并说明原因。

（4）指出甲、乙两地的板块边界类型，及相应的地貌。