两面墙之间的角度是90度。

The ___angle between the two walls is 90 degrees.

由两条垂直线形成的角称为直角。

An ___angle formed by two perpendicular lines is called a right angle.

航空法规要求进近角度必须保持在至少45度。

Aviation regulations require that the approach ___angle be maintained at a minimum of 45 degrees.