With his lips still trembling,he couldn't say a word.

问题描述:

With his lips still trembling,he couldn't say a word.
couldn't能换成can't吗?

最后不要换成can't.
句意为:他嘴唇仍然在颤抖,他一句话也说不出来了.
原因有二:
1.句意明显表示该动作发生在过去;
2.trembling表明该动作当时正在发生,也表明这两个动作也发生了.