some time ：某段时间,常与for连用.
e.g. Susie has been to Shanghai for some time.
苏西去上海有一段时间了。

sometime:副词,某个时候；形容词,前,过去的.
e.g. Bill went to the Great Wall sometime.
Bill曾经去过长城。

sometimes,有时.
e.g. Sometimes I go to school by taxi.
有时候我乘坐出租车去上学。

some times几次,几倍
e.g. His van is some times bigger than my car.
他的货车比我们的轿车大好几倍。