英 [ˈhɑːdli wen]；美 [ˈhɑːrdli wen]
意思
“hardly...when...” 是一个固定的时间状语从句结构，意思是“一……就……”。“hardly” 本身有“几乎不；刚刚”的意思，“when” 引导时间状语从句。这个结构强调两个动作发生的时间间隔非常短，几乎是紧接着的。
用法要点
“hardly” 后面通常接过去完成时，即 “had + 过去分词” 结构，表示第一个动作发生在过去的过去；“when” 后面接一般过去时，表示第二个动作紧接着第一个动作发生。
当 “hardly” 位于句首时，句子要用部分倒装结构，即将助动词 “had” 提前到主语之前。
例句
Hardly had I arrived home when it started to rain heavily.（我刚到家，就开始下大雨了。）
She had hardly sat down when the phone rang.（她刚坐下，电话就响了。）
Hardly had the movie begun when someone in the audience started to snore.（电影刚一开始，观众中就有人开始打呼噜了。）
He had hardly finished his speech when the audience burst into applause.（他刚结束演讲，观众就爆发出掌声。）
Hardly had the bell rung when the students rushed out of the classroom.（铃声刚一响，学生们就冲出了教室。）
The children had hardly gone to bed when their parents started to watch TV.（孩子们刚上床睡觉，他们的父母就开始看电视了。）
Hardly had the plane taken off when the passengers felt a strange vibration.（飞机刚起飞，乘客们就感觉到一阵奇怪的震动。）
I had hardly opened the book when I found a beautiful bookmark inside.（我刚打开书，就发现里面有一个漂亮的书签。）
Hardly had the chef put the dish on the table when the guests reached for their forks.（厨师刚把菜放在桌上，客人们就伸手去拿叉子了。）
She had hardly entered the room when she noticed the new painting on the wall.（她刚走进房间，就注意到墙上的新画了。）
Hardly had the sun risen when the farmers started working in the fields.（太阳刚升起，农民们就开始在田里劳作了。）
The athlete had hardly crossed the finish line when he collapsed from exhaustion.（运动员刚冲过终点线，就因疲惫而倒下了。）
Hardly had the store opened when customers flooded in.（商店刚开门，顾客就涌了进来。）
He had hardly closed his eyes when a loud noise woke him up.（他刚闭上眼睛，一声巨响就把他吵醒了。）
Hardly had the party started when the lights went out.（派对刚一开始，灯就灭了。）
The driver had hardly turned the corner when he hit a pothole.（司机刚转过弯，就撞上了一个坑洼。）
Hardly had the singer started singing when the audience began to sing along.（歌手刚一开始唱歌，观众就开始跟着唱了。）
I had hardly parked the car when I realized I had left my keys inside.（我刚停好车，就意识到我把钥匙落在车里了。）
Hardly had the meeting started when there was a knock on the door.（会议刚一开始，就有人敲门。）
She had hardly finished writing the letter when she heard a knock at the window.（她刚写完信，就听到有人敲窗户。）
近义词
scarcely...when...：意思与 “hardly...when...” 完全相同，也是表示“一……就……”，用法也一样，“scarcely” 后面接过去完成时，“when” 后面接一般过去时，位于句首时也要部分倒装。例如：Scarcely had we sat down when the waiter came to take our order.（我们刚坐下，服务员就来点菜了。）
no sooner...than...：同样表达“一……就……”的意思。“no sooner” 后面接过去完成时，“than” 后面接一般过去时，位于句首时句子要部分倒装。例如：No sooner had he seen the police car than he ran away.（他一看到警车就跑了。）
反义词
“hardly...when...” 强调两个动作紧接着发生，从语义相反角度来说，没有特别精准对应的反义词组。但如果要表达两个动作间隔时间长，可以用一些描述较长时间间隔的短语，比如 “long after...（在……之后很久）” 。例如：Long after he left, she finally decided to move on.（在他离开很久之后，她最终决定继续前行 。）