新手问题，时间的 [ 新手入门 ]

打开网页提示这个date()

[<a href='function.date'>function.date</a>]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'UTC' for '8.0/no DST' instead 
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说错误在配置中的这个里面 51 Copyright &copy; <?php echo date('Y'); ?><?php date_default_timezone_set('UTC')?> by My Company.<br/>

新手不是太懂，求说明，本人刚刚学习百度谷歌里面没见到，可能是问题是在太简单了。