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The idea of television, transmitting pictures through the air or over wires, has been around since the late 19th (36) . But it wasn’t until 1925, when J. L. Baird, a Scottish (37) . became the first to electrically transmit moving pictures, that television became a (38) . Baird’s first television was a mechanical system consisting of several moving parts. It had a small (39) onto which pictures were transmitted 10 times per second at 30 lines of resolution (分辨率). With the help of a photoelectric cell (光电管), bright and dim light were (40) into an electrical signal and sent via radio waves. In June 1925, Baird transmitted the (41) of a human face, winking and smiling from one room of the laboratory to another, without the aid of (42) or wires. Television truly came into its own in the 1930s with the advent of the cathode-ray tube (阴极射线管), which allowed for electronic line-by-line scanning of (43) . With the help of the Radio Corporation of America and an improved cathode-ray tube, the first all-electronic TV was demonstrated in 1932. (44) . As television’s evolution continues, high-definition (分辨率) digital TV is supposed to replace today’s 625-1ine sets with 1,050 or more lines of resolution. (45) . This trend has developed very fast. (46) .