仔细阅读下面的短文，短文中有10个空格或画线句子。请按照每小题括号内的具体要求完成语法填空、词形变化、句子合并、句子改写以及病句改正等。答案填写在标号为1～10的对应位置。

Most young people only get seven hours 　　1　　(介词)sleep each night, 　　2　　(对比连词)they actually need nine hours．And 　　3　　(make)up for lost sleep during the week by sleeping 　　4　　(介词)weekends doesn’t really work．In fact, sleeping late may actually do you much harm．You have sleep problems．　　5　　(合并为主从复合句)What happens if you don’t 　　6　　(谓语动词)enough sleep? If 　　7　　(人称代词)sleep problem continues for a few nights, you could suffer serious 　　8　　(problem)．　　9　　 Lack of sleepy can affect learning and memory．(改正错误)　　10　　(比较级), sleep difficulties could lead to anxiety or depression(抑郁)．