Often you know from experience how long it takes you to write a short essay,to study for a quiz,
or to review for a final exam.请问Often you know from experience和how long it takes you to write a short essay,to study for a quiz,or to review for a final exam.意思是:通常你从经验中知道 多长时间写一短文,准备一个测验,复习期末考试.