On doing sth

On doing sth keep on doing sth work on doing sth造句? 有spend.on doing sth spend ...on(in) doing sth ---------------------------------- spend on sth 等于spend doing sth spend doing sth和spend on sth keep doing sth.keep on doing sth.go on doing sth.continue do go on doing sth.和keep doing sth.的区别 go on to do sth.与go on doing sth. work on doing sth还是work on to do sth? go on doing sth,go on to do sth,continue doing sth,continue