Hardly had she walked out of the woods ＿＿＿ she heard the strange scream coming from behind

问题补充：

Hardly had she walked out of the woods ＿＿＿ she heard the strange scream coming from behind a tree.

答案：

解析：

hardly...when...表示“一……就”。注意，主句主谓要用部分倒装。