点击下方单词,选择对的这个单词
ph.
1. at a previous time
e.g. at one time he loved herher erstwhile writingshe was a dancer once
Synonym: onceformerlyerstwhileerst
2. simultaneously
e.g. he took three cookies at a time
Synonym: at a timeat once
多通过句子记忆单词，而不是单独死记硬背。
