a. not having an identifying mark
a. 未被注意的, 无记号的, 无标志的
1. The road was unmarked, making it hard to find the right direction.
这条路没有标记，让人很难找到正确的方向。
2. She wore an unmarked dress to the party, which made her stand out.
她穿了一件没有标记的裙子参加聚会，这让她显得很特别。
3. The package was unmarked, so I didn't know who it was from.
这个包裹没有标记，所以我不知道它来自哪里。