（1) since +过去一个时间点(如具体的年、月、日期、钟点、1980, last month, half past six)。
I have been here since 1989.
（2) since +一段时间+ ago
I have been here since five months ago.
（3) since +从句
Great changes have taken place since you left.
Considerable time has elapsed since we have been here.
（4) It is +一段时间+ since从句
It is two years since I became a postgraduate student.
Young For You—2015年武汉中考特别策划
考前
考中
考后
考前饮食
考前心理
考前冲刺
中考时间
中考作文
中考真题
中考查分
中考分数线
2011-2014年武汉各区中考分数线汇总
武昌区
江岸区
江汉区
硚口区
汉阳区
青山区
（1) since +过去一个时间点(如具体的年、月、日期、钟点、1980, last month, half past six)。
I have been here since 1989.
（2) since +一段时间+ ago
I have been here since five months ago.
（3) since +从句
Great changes have taken place since you left.
Considerable time has elapsed since we have been here.
（4) It is +一段时间+ since从句
It is two years since I became a postgraduate student.
Young For You—2015年武汉中考特别策划
考前
考中
考后
考前饮食
考前心理
考前冲刺
中考时间
中考作文
中考真题
中考查分
中考分数线
2011-2014年武汉各区中考分数线汇总
武昌区
江岸区
江汉区
硚口区
汉阳区
青山区