他还发现苹果表皮结实，但厚度不够。

He found that apples had strong skin but not enough mass.

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保护层厚度不够导致钢筋外露引起锈蚀，降低了桥梁的耐久性；

Secondly , protective layer thickness is too thin to protect concrete reinforced bar and reduce durability.

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用带刻度的钢针抽查厚度，如发现厚度不够，补喷或铲掉重喷，用锤子敲击检查空鼓，发现空鼓应重喷。

Belt Calibration checks the wire thickness, thickness found enough to make up for re-jet spray or shoveled away with a hammer percussion hollowing inspection found hollowing should re-sprayed.

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