产生原因：振捣后没有用拖板、刮尺抹平；混凝土未达终凝就在上面行人和操作。

Reasons: No scraping work after vibration; People walks or works on concrete before final set.

youdao

其他功能还包括一个黑色橡胶表带，防刮蓝宝石水晶，30米(99英尺)和耐水性。

Other features include a black rubber strap, scratch-resistant sapphire crystal, and water resistance to 30 meters (99 feet).

youdao

其他功能还包括一个黑色橡胶表带，防刮蓝宝石水晶，30米(99英尺)和耐水性。

Other features include a black rubber strap, scratch-resistant sapphire crystal, and water resistance to 30 meters (99 feet).

youdao