1. be ashamed of (doing) sth 对(做)某事感到羞愧或惭愧。如：
You really ought to be ashamed of that. 你实在应该对此感到惭愧。
He was ashamed of asking [having asked]such a simple question. 他由于问了这样简单的问题而感到难为情。
He is ashamed of his failure [having failed]. 他对自己的失败感到羞惭。
比较以下同义句型：
I am ashamed of that. / I am ashamed of myself for that. 我对此感到羞愧。
He is ashamed of being poor. / He is ashamed of himself for being poor. 他因为穷而感到羞惭。
2. be ashamed to do sth
(1) 因感到难为情或感到差耻而不愿某事。如：
I am ashamed to say so. 这样说我不好意思。
He was too ashamed to ask for help. 他不好意思请求帮助。
(2) 对做某事而感到羞愧或惭愧。如：
You should be ashamed to tell such lies. 撒这样的谎你应该感到羞愧。
He was ashamed to have made some careless mistakes. 他因出了些很粗心的差错而感到惭愧。
注：该用法有时可换成 that 从句。如上面最后一句也可说成：
He was ashamed that he had made some careless mistakes.
再比较：
他因说谎而感到羞惭。
正：He was ashamed of having lied.
正：He was ashamed to have lied.
正：He was ashamed that he had lied.