目前对飞船只进行了一些低海拔的飞行测试，平流层的测试则仅仅是由气象探测气球负载着规模缩小的模型原型机来进行的。
So far, apart from some low-altitude test flights, the only stratospheric tests have involved a scaled-down version tethered to a weather balloon.
此外，原型机可以直接根据计算机模型制造出来。
Moreover, prototypes can be built directly from the computer model.
他发明了好几种洁手装置的原型机，这些机器可以悬挂在墙上，跟那种便携式的电动模型一样，大小相当于一支较大的电动牙刷。
He has developed several prototypes of hand-cleaning devices that can be mounted on walls, as well as a portable, battery-operated model the size of a large electric toothbrush.
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