semicircular key

例句：

1. 1. The sun is shining through the semicircular window.
   太阳透过半圆形的窗户照射进来。
2. 2.The team decided to form a semicircular line for the game.
   队伍决定为了比赛形成半圆形阵线。
3. 3. The artist drew a semicircular shape on the canvas.
   艺术家在画布上画了一个半圆形的形状。