Private daycare or nannies are uncommon in Germany, and most often only chosen if government-funded or church-funded daycare is not available.

请问，句中 most often only chosen 是什么结构？可否加上动词 are，变成Private daycare or nannies are uncommon in Germany, and most often only are chosen if government-funded or church-funded daycare is not available.谢谢老师。