Just as a snowflake requires a nucleus to spur the formation of its intricate crystal structure - a catalyst was required to spur the formation of the desired community.
一片雪花，必须有凝结核才能形成其复杂的晶体结构。在我们期望建立的群体中，同样需要这样的催化剂。
2
The formation mechanism of transition part shoal, function and arrangement of spur dike and training dike are expounded and living examples are given for explanation.