<!<del>StartFragment&gt;<br/><br/>I found the below sentence in a dictionary.<br/><br/>His quality of life <u><b>has improved</b></u> dramatically since the operation.<br/><br/>But sometimes it seems that "His quality of life <u><b>has been improved</b></u> dramatically since the operation." is OK. <br/><br/>Can I use both of them?<br/><br/>Even if both are OK, is there any difference of nuance? <br/><br/><br/><br/>