Directions: There are 20 blanks in thefollowing passage. For each blank there are four choices marked A ). B), C) and D) on the right side of the paper. You should choose the ONE that bestfits into the passage. Then mark the corresponding letter on Answer Sheet 2 with a single line through the centre. Design of all the new tools and implements is based on careful experiments with electronic instruments. First,a human "guinea pig" is tested using a 67 tool.Measurements are taken 68 the amount of work done,and the buildup of heat in the body. 69 joints and stretched muscles cannot 70 as well, it has been found, 71 joints and muscles in their 72 positions.The same person is then tested again, using a tool designed according to the suggestions made by Dr. Tichauer. All these tests have shown the great 73 of the new designs over the old. One of the electronic instruments used by Dr. Tichauer,the myograph( 肌动描记器), _74 visible through electrical signals the work done by human muscle. Another machine 75 any erous features of tools, thus proving information upon 76 to base a new design One 77 of tests made with this machine is that a tripod stepladder is more 78 and safer to use than o'ne with four legs. This work has 79 the attention of efficiency experts and time-and-motion-study engineer, but its value goes far 80 that. Dr. Tichauer's first _81 is for the health of the tool user. With the 82 use of the same tool all day long on _83 lines and in other jobs, even light 84 work can put a heavy stress on one small area of the body. In time, such stress can cause a disabling disease. 85 , muscle fatigue is a senous safety 86. 67.