Since +時(shí)間點(diǎn)，具體時(shí)間自從、、、、以來(lái)，從、、、以后” 用來(lái)說(shuō)明動(dòng)作起始時(shí)間
I have been in Beijing since 2010.
For + 時(shí)間段，用來(lái)說(shuō)明動(dòng)作延續(xù)時(shí)間長(zhǎng)度，因此句中的謂語(yǔ)動(dòng)詞，也應(yīng)該是延續(xù)性動(dòng)詞。
I have been in Beijing for one year.
for +一段時(shí)間
since +句子
since +一段時(shí)間+ ago
since +時(shí)間點(diǎn)
例如 he has been dead for three years
he has been dead since three years ago
He has studied English since 2003
He has studied English since he was ten years old