I don't want to leave a bitter taste in his mouth.
我不想给他留下不愉快的印象。
leave a bitter taste in his mouth直译过来就是：“在他嘴里留下苦味”，这个短语的正确意思是：“给他留下不愉快的印象”。因此，当美国人说"I don't want to leave a bitter taste in his mouth."时，他/她要表达的意思就是:"I don't want to leave him a bad impression."、"I wouldn't like to leave him an unhappy memory."。
情景对白：
Shirley: You look pale today. Why don't you ask for a leave?
雪莉：你脸色很苍白啊，为什么不请假休息呢？
Jane: Well, I have to accompany one of our foremost clients to our factory. I don't want to leave a bitter taste in his mouth.
简：哎，我得陪一个重要客户去工厂。我不想给他留下不愉快的印象。
搭配句积累：
①You can ask the boss since you cannot make heads or tails of it.
你搞不懂可以问老板啊。
②You can go back to have a rest and do it tomorrow.
你可以先回去休息，明天再接着做。
③Don't worry. I will try my best to finish the mission.
尽管放心吧，我会尽力完成这次任务的。
④I will go to visit the client myself.
我还是亲自去见客户吧。
单词：
bitter adj. 苦的
As I said, babies love the taste of sweet and hate the taste of bitter.
像我前面讲的，婴儿喜欢甜味，讨厌苦味。
Whether one's situation feels bitter or sweet is often subjective.
一个人的处境是苦是乐常是主观的。
If you wish to be the best man, you must be prepared to suffer the bitterest of the bitter.
吃得苦中苦，方为人上人。
