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举一反三
【单选题】The invention of both labor-saving tools and tools of intelligence is rarely accidental. Instead, it is usually the product of human need【C1】______is truly the mother of invention. People usually devi...
A.
imagination
B.
creativity
C.
necessity
D.
accident
【单选题】'念珠斑'的含义是（ ）。
A.
乌梢蛇背部有黑色办斑纹，习称'念珠斑'
B.
蕲蛇部背部有黑色办斑纹，习称'念珠斑'
C.
金钱白花蛇的腹部有黑色办斑纹，习称'念珠斑
D.
蕲蛇的腹部有黑色办斑纹，习称'念珠斑
E.
金钱白花蛇背部有黑色办斑纹，习称'念珠斑'