有网友提问如下：
下面的句子是 2012 年陕西卷的一道高考题：
Hot as the night air was, we slept deeply because we were so tired after the long journey.
我对句中的 sleep deeply 有点疑问，老师不是说要表示“睡得很熟”，应该用sleep fast 吗？这里怎么用了 sleep deeply 呢？还是两种说法都可以吗？如果 sleep fast 和 sleep deeply 都可以说的话，那还有没有其他说法呢？（即表示“睡得很熟”的其他表达）
1. 汉语说“睡得很熟”，若使用动词sleep，英语可以有以下常用表达：
(1) sleep deeply
She slept deeply but woke early. 她睡得很熟但醒得很早。
He was exhausted and slept deeply. 他筋疲力尽，睡得很沉。
(2) sleep sound
He sleeps sound every night. 他每晚都睡得很熟。
He was lying in bed, sound asleep. 他躺在床上，睡得正香。
(3) sleep soundly
She’s sleeping soundly. 她睡得很死。
Did you sleep soundly last night? 你昨晚睡得好（睡得沉）吗？
(4) sleep heavily
The baby was sleeping heavily. 宝宝睡得很沉。
In spite of this, I slept heavily. 尽管如此我还是睡得很熟。
2. 汉语说“睡得很熟”，若使用形容词asleep，英语可以有以下常用表达：
(1) fast asleep
He seems to be fast asleep. 他似乎睡得很熟。
They were both fast asleep in their cots. 他们俩在婴儿床上酣睡着。
说明：副词 fast 修饰形容词 asleep 的用法很普通，但它修饰动词 sleep 的用法却很少见。
(2) sound asleep
She is still sound asleep in her bed. 她仍在床上睡得很熟。
Turning over, she was soon sound asleep again. 她翻了个身，很快又沉沉睡去。
(3) soundly asleep
Don’t wake her up—she is soundly asleep. 别吵醒她，她睡得正香。
She was too soundly asleep to hear Stefano’s return. 她睡得太熟，没有听见斯蒂芬诺回来。
(4) deeply asleep
The boy was very deeply asleep. 男孩睡得很熟。
You will be deeply asleep by the time we get home. 等我们到家时，你会睡得很熟了。