表示的时间不同
present 表示目前 现在
past 意思是过去的昔日的刚过去的刚结束的从前的
Present 例句：
The present crisis is worse than any that have gone before. 目前的危机比以往任何一次危机都严重。
He doesn't feel fulfilled in his present job.目前的工作未能让他感到满足
Past 例句：
He has matured a great deal over the past year. 经过过去这一年，他成熟了许多。
In some sports you're past it by the age of 25. 在某些运动中，人过25岁就难有作为了。
