Doing morning exercises every day can keep you healthy. These two sentences have the same meaning and are interchangeable.
Keep is a transitive verb, which can mean "keep a state unchanged" with adjectives, and keep (sth). ) maintain is also a transitive verb, which means "keep things in their original state or standard" adj.maintain something.
Keep is followed by a gerund, which can mean "continue to do an action, continue to do an action"; If you still want to use maintenance at this time, you can't use that gerund later, because maintenance doesn't mean it.
They have been writing to each other. They keep in touch with each other.
Therefore, in the second sentence of western culture, it is necessary to keep eye contact in conversation. In western culture, it is necessary to keep eye contact in conversation. Eye language is a word I made up, which means to tell you that if you use keep, you should use gerund after this sentence. )
Therefore, you will find that sometimes, word collocation is the key to decide which word you choose to use.