未分类题

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 【C1】______ tool. Measurements are taken 【C2】______ the amount of work done, and the buildup of heat in the body. 【C3】______ joints and stretched muscles cannot 【C4】______ as well, it has been found, 【C5】______ joints and muscles in their 【C6】______ 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 【C7】______ of the new designs over the olD.
One of the electronic instruments used by Dr. Tichauer, the myograph, 【C8】______ visible through electrical signals the work done by human musclE.Another machine 【C9】______ any dangerous features of tools, thus proving information upon 【C10】______ to base a new design. One 【C11】______ of tests made with this machine is that a tripod stepladder is more 【C12】______ and safer to use than one with four legs.
This work has 【C13】______ the attention of efficiency experts and time-and-motion-study engineer, but its value goes far 【C14】______ that. Dr. Tichauer's first 【C15】______ is for the health of the tool user. With the 【C16】______ use of the same tool all day long on 【C17】______ lines and in other jobs, even light 【C18】______ work can put a heavy stress on one small area of the body. In time, such stress can cause a disabling diseasE.【C19】______ , muscle fatigue is a serious safety 【C20】______ .
【C1】
A.regular
B.usual
C.common
D.constant