The abacus (算盘) was a great invention in ancient China. The abacus ___61___ (invent) on the basis of

阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。
The abacus (算盘) was a great invention in ancient China. The abacus ___61___ (invent) on the basis of small rods (棒). Later, with the ___62___ (develop) of productivity, the amount of calculation was ___63___ (great). And calculation with counting rods limited the calculation. Thus, people invented a more ___64___ (advance) counter—the abacus.
With the application of the abacus, people summarized many abacus rhymes (珠算口诀), ___65___ (increase) the calculating speed. By the time of the Ming Dynasty, people could use the abacus in addition, subtraction, multiplication and division, ___66___ were widely used in calculating weight, amount, space and volume.
Since it was easy to make or buy ___67___ abacus. And it was also easy to remember abacus rhymes. The abacus was widely used in ancient China. Later, the abacus was ___68___ (gradual) spread into Japan, Korea, America and some countries and regions in Southeast Asia.
People find that using abacuses can improve thinking and practical abilities in addition ___69___ providing convenient calculation. Since it ____70____ (require) cooperation of mind, eye and hand, it is a good way to improve the comprehensive reaction ability.
【答案】61. was invented    
62. development    
63. greater    
64. advanced    
65. increasing    
66. which    67. an    
68. gradually    
69. to    70. requires
【解析】