直到那时他才意识到
only then───始；乃；直到那时（后面的句子要倒装）
then he───然后他
he did───他做到了（did是do的过去式）
realize───vt.实现；认识到；了解；将某物卖得，把(证券等)变成现钱；变卖
he did that───他做到了
did not he───他不是吗
when did he───他什么时候来的
did he speak───他说话了吗
what he did───他做了什么
did he realize that he had been wrong.───他从来没有失去过自制力。
Only then did he realize his mistake.───当时他就认识到了自己的错误。
Only then did he realize that he was wrong.───只有那时他才认识到他错了。
Only then did he realize that the train might have hit something.───直到那时，他才意识到可能发生撞车了。
Only then did he realize that he was far from ready to marry the girl.───直到那时他才意识到自己还远没有作好准备娶这个姑娘。
Only then did he realize that he had been wrong.───直到那时他才知道他错了。
Only then did he realize that he was not the right man for the job.───只有那时候他才意识到他不适合做这工作。
eg: Only then did he realize that he had made a mistake.───只有到那个时候，他才认识到自己犯了个错误。
Only then did he realize that he had made a mistake.───直到那时他才知道他犯了一个错
Only then did he realize that he had been wrong.