| 摘要 |
A toothbrush comprises both soft and hard bristles. The soft bristles are longer while the hard bristles are shorter. With less force, only the soft bristles are used, giving minor cleaning and gum massaging. With stronger force, the hard bristles will be used, giving more effective cleaning, especially the space between the teeth. The hard bristles are implanted away from the edge of the bristle pattern so they are kept from being bent outward. Some bristles at the edge of the pattern are cut shorter to give the hard bristles a chance to get into space between the teeth.
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