Lecture with formulas on the blackboard in front of studentsLecture with formulas on the blackboard in front of students
Snowy mountains and the sky in the blue expanse of the lakeSnowy mountains and the sky in the blue expanse of the lake
Blue river at the foot of green mountains, green trees on the right bank against the sky in white cloudsBlue river at the foot of green mountains, green trees on the right bank against the sky in white clouds
Quiet beautiful sunset in the countryside in natureQuiet beautiful sunset in the countryside in nature