[单选题]飞机在空中巡航时,自动安定面配平正常工作的结果:
A.升降舵与飞机的纵轴方向一致
B.升降舵回到安定面的中立位
C.升降舵保持上偏
D.升降舵保持下偏

Highly intelligent and strong, elephants are the largest land animals and are among the longest-lived, with life spans of 60 years or more. Healthy, full-grown elephants have no natural enemies other than humans.
Elephants once lived on every continent except Australia and Antarctica, but elephants today are restricted to Africa and parts of Southeast Asia. They occupy a wide range of environments in Africa and Southeast Asia: grasslands, marshes, forests, deserts, and mountains. They need great quantities of food to support their massive size. They also need a lot of drinking water and so are restricted to areas with adequate water.
Throughout history, people have prized elephants for their great size and strength. On the battlefield, elephants have defeated the enemies. Elephants also have been trained to carry heavy supplies through the forests where they once lived.
Elephants have long been honored, and in Thailand, India, and other Southeast A
A. highly intelligent and strong, elephants are the largest land animals
B. elephants are among the longest-lived, with life spans of 60 years or less
C. healthy, full-grown elephants have natural enemies rather than humans
D. human beings bring great harm to the elephants