PAL and SECAM are standards used in other countries. RGB stands for red, green, and blue - the colors of light used to create an image in a color tv set and is often used as a format name for computer monitors.
The yo-yo was first used by hunters as weapons. They were wooden disks on strings. In the 1920s, a man from the U.S. named Donald Duncan made the yo-yo into a toy after he visited the Philippines.
4. Which of the following is concerned with the study of characteristics, origin and development of land forms?