可以
在現(xiàn)在完成時的句子中,already常用于肯定句,yet常用于否定句和疑問句,但yet還有其他用法.1.用于否定句中,意思是還、尚、迄今、到那時”.例如 he is not yet here.他還未到.at three o”clock they had not yet decided whether to play basketball or not.三點鐘時他們尚未決定是否去打籃球.2.用于疑問句中,意思是已經(jīng)”.例如 is everything ready yet 一切都準(zhǔn)備好了嗎?3.與比較級連用,意思是更”.例如 you must work yet harder.你還需更努力地工作.4.與once ,again ,another 連用,意思是再”.例如 he has made yet another mistake.他又犯了一個錯誤.5.用于肯定句中,意思是仍然、還得”.例如 she is yet a child.她還是個孩子.6.用作并列連詞時,意思是然而、可是”.例如 he studied hard yet he failed.他學(xué)習(xí)努力,可是考試仍未及格.
不必加逗號