A sentence/a part of the sentence is underlined. Four alternatives are given to the underlined part which will improve the sentence. Choose the correct alternative and click the button corresponding to it. In case no improvement is needed, click the button corresponding to "No improvement". Electricity has modernized the march of modern events.
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?