It is /has been +时间 since +过去时
两种用法其实是一样的,用is陈述情况,用has been 强调从.起到现在的时间长度
It is three years since I began to learn English.=It has been three years since I began to learn English
It is /has been +时间 since +过去时
两种用法其实是一样的,用is陈述情况,用has been 强调从.起到现在的时间长度
It is three years since I began to learn English.=It has been three years since I began to learn English