正立摆放的圆锥，水平投影是一个圆，另两面投影是三角形。The projection of a cone which is set to upright must be one circle frame and two triangles.
举一反三
- 正立摆放的圆锥，水平投影是一个圆，另两面投影是三角形。The projection of a cone which is set to upright must be one circle frame and two triangles.
- 正立摆放的圆锥，水平投影是一个圆，另两面投影是三角形。The projection of a cone which is set to upright must be one circle frame and two triangles. A: 正确 B: 错误
- 四棱锥的投影，有两面投影外轮廓一定是三角形（）。There are two side views having triangles for the projection of a square pyramid.
- 中国大学MOOC: 四棱锥的投影，有两面投影外轮廓一定是三角形（）。There are two side views having triangles for the projection of a square pyramid.
- 四棱锥的投影，有两面投影外轮廓一定是三角形（）。There are two side views having triangles for the projection of a square pyramid. A: 正确 B: 错误