Most tests require collecting cells by webbing saliva in the mouth and sending it to the company for testing.All tests require a potential candidate with whom to compare DNA.这句话该怎么理解呢?
...时间或过去时间。(should+do=现在或过去时间)It's lucky that the weather should be (=is/was) so fine.参考:https://www.cpsenglish.com/question/24188Donna 老师说:“...in case从句中...,事实上,should / might+动词原形这样的虚拟语气不仅可用来表示将来...