pencil compass

• 圆规

pencil compass的用法和样例：

例句

1. Use your compass to bisect an angle.
   用圆规把一个角二等分。
2. Trisecting an arbitrary angle with a compass and straightedge was one of the famous ancient Greeks unsolved construction problems.
   用直尺和圆规三等分一个任意的角是古希腊著名的构造问题之一。