Jack is a 16-year-old boy. Last summer, he wanted to have a nice1.He asked his parents for the money.But his parents said he must get it by himself.But 2could he get one?

    One day，on his way home，he was thinking about this.Not many people wanted to ask children to work3them.Maybe he could sweep away the snow for the neighbours.However，it was not4.He had to wait a long time for that. Just at the moment，he saw Tom，one of his classmates，working in a5shop.

    "I could do that，"he thought.He asked Tom some questions.He learned that it took Tom about three hours a day to do the job6he could get twenty dollars each week.Then Tom gave him the telephone number of the book shop manager.Jack almost 7 home."Mum，I have good news to tell you，"Jack said.After he told his mother that，she said,"I think it's a8idea."

    "I will9the manager tomorrow,"said Jack，"After all，I'm going to be a businessman.''Jack's mother looked 10at him and smiled.

    After the summer holiday，Jack got the bike which he dreamt of.

磁感线从磁铁的　____ 极出发，回到磁铁的　____ 极；磁感线上某点的____ 方向表示该点的磁场方向．

给出如下四个命题：
①若“p且q”为假命题，则p、q均为假命题；
②命题“若$x\ge 2$且$y\ge 3$，则$x+y\ge 5$”的否命题为“若$x<2$且$y<3$，则$x+y<5$”；
③在$△ABC$中，“$A>{45}^{°}$”是“$\sin A>\frac{\sqrt{2}}{2}$”的充要条件.
④命题 “$\exists x_0\in R,e^{x_0}\le 0$”是真命题. 其中正确的命题的个数是（     ）

写出5个与 $\frac{9}{4}$ 一样特征的分数____。