在创建另一个 椭圆选区 时按住 Alt 键，这样就能用这个圆减去原来那个外圆，于此你就得到下面展示的示意图那样的按钮灯外环厚度。

While holding Alt create another elliptical selection so that you would subtract the original selection to leave you with the thickness of the outer button's light as shown in the illustration below.

youdao

豪迪·苟迪使用数盏加热灯向人们展示了经过技术处理后的双层玻璃窗的隔热效果。美国小餐馆通常使用这种加热灯对食物保温。

Goudey demonstrates how the treated double-pane Windows work with the help of heat lamps - the kind that diners use to keep food warm.

youdao

白炽灯是通过世博会的展示才被普及使用的。

The incandescent lamp was introduced into people's life through its first display in a World's Fair.

youdao