I fell back and hurt my head.

我向后跌倒，把头跌伤了。

《新英汉大辞典》

I had had a long day, so after I unpacked, I fell back on the bed exhausted.

忙了一整天的我，精疲力尽，整理好行李后，就一头倒在床上。

youdao

Why, don't you know? ' asked one of them. ' The police have found Mr Spenlow dead! ' I fell back, shocked.

“怎么，你不知道？”其中一位回答，“警察发现斯本罗先生死了！”我大为震惊，向后倒去。

youdao

After 15 minutes they stopped and eventually, uneasily, I fell back to sleep.

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"I woke up and my doctor gave me the news, and I fell back down in grief and I started to cry, " Jackson said.

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In bed I would lie on my back practicing until I fell asleep.

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