prior to是介词短语。
在……之前；居先
It is important to enrich the soil prior to planting.
栽种之前给土壤施肥很重要。
This duty is prior to all others .
这个职务比其他一切职务都重要。
We received no notification prior to today 's date .
我们在今日之前未获通知。
I called on her prior to my departure .
我动身前去看过她。
Glass bead gels need not be hydrated prior to use .
玻璃珠凝胶在使用之前不需要水化。
Some people proposed polymerizing the glycerine prior to nitration .
有人建议在硝化之前，把甘油聚合。
