There is a beautiful waterfall made of artificial rock in this park.

The geology of this area is mainly composed of serpentinite.

This stratum is mainly composed of mudstone.

This area is rich in pitchstone.

The striped shore crab is a creature often seen in rocky areas.

He was playing the guitar at the street corner.

The opposite angles of a quadrangle intersect each other.

In this right triangle, since one angle is 30 degrees, its complementary angle is 60 degrees.

He is learning calligraphy with a square brush.

We need to calculate the azimuth of this building.