The main material of most masks is polypropylene.

大多数口罩的主要材料是聚丙烯。

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Main material of door: Solid wood, HDF board, Quality Steel Plate.

主要材质门：实木，高密度纤维板板，优质钢板。

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Pear vinegar is a kind of fruits vinegar made of pear as the main material by crushing.

梨醋是以梨为主要原料，经破碎、榨汁、酒精发酵、醋酸发酵而成的一种果醋。

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Iron ore, the main raw material of steel, changed the lakes area and the nation.

VOA: special.2009.11.11

The connective tissue is one of those four main types of tissue, they're supporting material - supporting tissues that surround other cells in the body and give the cell - and give the body much of its mechanical property.

结缔组织是四种主要组织类型中的一种,它们是支持物--是,包围在体内其它细胞周围的支持组织,并赋予身体大部分的机械性能

耶鲁公开课 - 生物医学工程探索课程节选

For Dow Chemical,the main focus will be producing material from algae that can be used to make plastics.

VOA: standard.2009.09.02

For 3, once nylon had been discovered and proven useful, the race was on, given the supply of cheap oil (the main raw material) post WWII, from the Arabian Gulf.

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The mine was shut down by the U.S. Mine Safety and Health Administration due to the unsafe buildup of sand and concrete material in the main shaft of the mine.

FORBES: Hecla's Lucky Friday Mine Rehabilitation Slightly Ahead Of Schedule, Restart In Early 2013

Yet this is not to deny his main point: the pursuit of material comforts does not always lead to happiness.

ECONOMIST: Why don't rising incomes make everybody happier?