下面短文中有10处错误。请在有错误的地方增加，删除或修改某个单词。 增加：在缺词处加一个漏词符号（∧），并在其下面写上该加的词。 删除：把多余的词用斜线（﹨）划掉。 修改：在错的词下划一横线，并在该词下面写上修改后的词。 注意：1，每处错误及其修改均仅限一词。 2，只允许修改10处，多者（从第11处起）不。 A survey basing on 1,000 students found that 80% of senior students slept less than nine hours every night. Too much homework being given by school teachers is the main cause. Another cause lies at students’ bad habits. Some students are absent-minded while doing their homework, and some wasting their after-class time. The third cause is some students have to get up earlier on weekdays to get to school which far away from home. Experts think the amount of homeworks for the students should be cut down. Beside, teachers should encourage their students make good use of their spare time.