ask sb to do sth到底是请求某人做某事，还是要求某人做某事，还是都可以，为什么，可以举一些例子吗？

ask sb to do sth到底是请求某人做某事，还是要求某人做某事，还是都可以，为什么，可以举一些例子吗？
"to let sb do something"
means to permit and allow somebody to do something.
"She lets him use her computer."
" to ask somebody to do something."
means to demand and request politely somebody to do something.
" She asked him to help her fix the device."