The dodder is one kind of annual autoecious weed of alfalfa, cosmopolitan weed quarantine object.

摘要菟丝子是苜蓿田中最常见一年生寄生性恶性杂草，是世界性杂草检疫对象。

New York is a highly cosmopolitan city.

纽约是一个高度世界性城市。