Another app lets musicians play virtual instruments by moving their arms through the air.

另外一款应用则帮助音乐家们凭空挥手来操作虚拟乐器。

And several countries have already built collections of small, cheap dishes and networked them into more powerful “virtual” instruments.

许多国家已经建造了一些廉价并能联网的小型天文观测装置，来组成了虚拟仪器。