The main cause was a poorly made crown with overhanging margins.
主要的原因是牙冠做的不好，周围有突出来的牙龈。
2
This dazzling gold crown that dates back almost 250 years is regarded as the main symbol of the Spanish monarchy, although rarely worn.
这顶耀眼夺目的黄金王冠可以追溯到差不多250年前，被看作西班牙王室的象征，但它很少被佩戴。
3
And there are obvious difference of stemflow among different species, the main factors that affect the stemflow are crown structure, diameter breast-high and crown width.