“明了地”的英语可以翻译为：legibly ...

申请签证时，要简单明了地说明申请理由。When applying for a visa state simply and clearly the reasons why you need it.我对他直接明了地说,他发疯了.I told him in so many words that he was crazy.我简单明了地解释了我的意思.I explained my meaning shortly but clearly....