小鸟能在天空中飞翔,靠的是翅膀;飞机能飞上蓝天,靠的是机翼;潜艇在大海里自由地航行,也需要有“翅膀”。潜艇的“翅膀”就是舵翼。人们称它为升降舵。由于它是水平地安装在潜艇上的,因此,人们又叫它水平舵。它能操纵潜艇上下升降,保持或改变潜艇在水中的深度。现代潜艇上都装有两个比较特殊的升降舵,一个安装在艇艏,一个安装在艇艉。艇艏的叫艇艏升降舵,艇艉的叫艇艉 Birds can fly in the sky, by the wings; the plane can fly in the sky, by the wing; submarine free sailing in the sea, but also need to have “wings.” Submarine's “wings” is the rudder wing. People call it an elevator. Because it is mounted horizontally on a submarine, people call it a horizontal helm. It can manipulate the submarine up and down to maintain or change the depth of the submarine in the water. Modern submarines are equipped with two more special elevator, one installed in the boat 艏, one installed in the boat 艉. Boat 叫 called boat 艏 elevator, boat 叫 called boat 艉