Nature of the usa. mountains, forest and clouds of the appalachian mountain systemNature of the USA. Mountains, forest and clouds of the Appalachian mountain system
Smoke is a stable dispersed system consisting of fine solid particlesSmoke is a stable dispersed system consisting of fine solid particles
An image showing system errors on the computer screenAn image showing system errors on the computer screen
Computer - system unit, mouse, video card, keyboardComputer - system unit, mouse, video card, keyboard