since前(即主句)用( 现在完成)时态,后(从句)用(一般过去时)时态
如
He has worked here since he came to China.
*******************************************************************
加油!不明白再问!如果帮到你,请及时采纳,谢谢!
*******************************************************************
温馨提示:答案为网友推荐,仅供参考