农民用覆盖物保护作物免受霜冻。

The farmer used a teg to protect the crops from frost.

用覆盖物保护幼苗免受恶劣天气的影响。

Protect the saplings from harsh weather by using a cover.

对磨损严重的部位，除采取用覆盖物加以保护外，还可调换位置使用。

Serious to wearing away place, except adopt outside trying to protect with covering, still can exchange the position is used.

结论：根管治疗的下颌磨牙冠缺损达牙冠三面者建议用覆盖牙尖的修复体修复，以保护牙体结构。

Conclusion: Within the limitations of this study, root-canal-treated mandibular molars with three surface defects was suggested to place the restorations of occlusal coverage.