_________(61)A.prevent B.preserve C.presume D.pre

1，－5，13，－29，______ A.－61 B.－39 C.39 D.61

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The purpose of the wearing rings used in a centrifugal pump is to _____.A.prevent an inter

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The main function of piston compression rings is to _______.A.prevent excessive cylinder l

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Setting a sealing equipment astern on the tailshaft can’t ____.A.prevent the seawater from

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According to the news item, partially hydrogenated oils are used to______.A．prevent heart

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61._________A. processesB. producesC. possessesD.

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_________(65)A.prevent B.define C.decide D.delay

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