a. not known or well known
a. 不熟悉的
1. She felt unfamiliar with the new city when she first arrived.
她初到新城市时感到很不熟悉。
2. The unfamiliar smell in the kitchen made me curious.
厨房里陌生的气味让我感到好奇。
3. It's normal to feel unfamiliar with a new language at first.
刚开始对一门新语言感到不熟悉是很正常的。