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A、
B、
C、
D、

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谐波齿轮由_________、_________和_________三个主要零件组成。
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Which of the following belong to abiotic diseases A、Diseases caused by too low or too high a temperature B、Diseases caused by nematodes C、Diseases caused by lack or excess of soil moisture D、Diseases caused by lack or excess of light E、Diseases caused by lack of oxygen F、Diseases caused by air pollution G、Diseases caused by nutrient deficiencies
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