If you had a motor here that was causing a paddle to move upanddown you could cause waves to form at one end of the tank and move from left to right.
如果这里有一个马达，使桨上下移动，就可以在水槽的一端形成波浪，从左到右扩散。
2
Many outboard brackets, like the one shown here, can be moved upanddown to raise and lower the motor.
许多舷外发动机支撑臂，就像上图中所示的那个一样，可以上下移动以使发动机抬起或下降。
3
A few years into their retirement they "sold everything they owned", bought a motor home, and drove it for more than a decade up, down and across America.