Look at the crying baby.
Look at the baby crying.
请问这两句都对吗？如果是都对的话，它们有不同吗？
▲你的两句话都对。
第一句：Look at the crying baby. 只有一种理解，马上目前分词 crying 理解为定语。
第二句：Look at the baby crying. 则有两种理解，既可将 crying 理解为定语（= Look at the baby who is crying；与前面一句同义），也可以将它理解为宾补。
▲对于“look at + 宾语 + doing sth”结构来讲，依据不一样的语境可能有多种不一样的使用方法。譬如：
1. 有时其中的 doing sth 为定语。如：
Look at the man sitting on the rock. 看那个坐在岩石上的人。
She looked at the eager faces waiting for her news. 她看了看那些期待着她的消息的热切的脸孔。
Look at that little boy wandering about—perhaps he’s lost his mother.看那个在那里徘徊的小孩子子——他可能是找不到他母亲了。
2. 有时其中的 doing sth 为宾补。如：
We are looking at him dancing. 大家在看他跳舞。
Just look at the rain pouring down! 瞧这雨下得多大!
That’s superb running—look at his legs pumping. 他跑得真棒——看他两条腿翻飞的样子！
He’s the picture of misery, isn’t he? Look at him standing there in the rain. 他看上去难过极了，不是吗？看他站在雨中的样子。
3. 有时其中的 doing sth 为状语。如：
I looked at Chris trying to gauge his reaction. 我看着克里斯，琢磨着他会作出哪种反应。
4. 有时其中的 doing sth 是动名词。如：
We have set up a task force to look at the question of women returning to work. 大家已经成立了一个工作组去调查妇女复工的问题。
