Campbell Remess is a teenager from Australia. He has been sewing (缝制) teddy bears for sick children for several years.

    The story____ (begin) in 2013 when Campbell was nine years old. He told his parents that he wanted to give Christmas gifts to children in hospitals. But his parents said no, because with nine children of their own, buying presents for sick children would just cost too much. The little boy didn't give up, however. He decided____(make) their presents by himself.

    Campbell made his first teddy bear with his mother's sewing machine in his bedroom. It was hard for him as he had never done this before. He downloaded (下载) patterns from the Internet and learned how to make a teddy bear by____(watch) videos online. It took him five hours to finish his first teddy bear. He can now make a teddy bear in an hour. He has also started a project called “Project 365 by Campbell” in which he____(try) to make a teddy bear every day.

    Young Campbell uses his pocket money to buy materials for making teddy bears. To make more pocket money, he helps his parents with housework whenever he is free. Sometimes, he also sells his teddy bears online____(raise) money for sick children. Many people ____ (encourage) by Campbell's story and they give away free materials to him.

    Campbell____ (give) away about 1,300 teddy bears so far. He is now busy making this year's teddy bears. He said that he had never thought of stopping and he would keep putting smiles on people's faces.

阅读材料，回答问题。

材料一：商鞅是首屈一指的利国富民伟大的政治家，是一个具有宗教徒般笃诚和热情的理想主义者。商鞅之法……此诚我国从来未有之大政策。—— ***

材料二：商鞅变法前，秦国各地度量衡不统一。为了保证国家的赋税收入，商鞅制造了标准的度量衡器商鞅方升……此外商鞅还规范了进位制度，统一了斗、桶、权、衡、丈、尺，规定六尺为一步，二百四十步为一亩，五十亩为一畦。—— 维基百科

材料三：商鞅一方面极力否认道德教化对人的劝导意义，主张唯有重刑才是禁奸止过的最好办法。另一方面又背离了罪刑相应的原则，主张轻罪重刑，甚至罪及无辜。他的这种重刑思想被其后的韩非继承并发展，对中国封建社会的刑法理论和实践产生了深远的影响，以至严刑峻罚、惩办威吓构成了中国两千多年封建社会刑法制度的一个重要特征，给广大人民带来了许多苦难。——《商鞅刑法思想及变法实践》

请回答：

① “在三角形 中，若 ,则 ”的逆命题是真命题；

②命题 或 ，命题 则 是 的必要不充分条件；

③ “ ”的否定是“ ”；

④ “若 ”的否命题为“若 ，则 ”；

其中正确的个数是（   ）

能自行发光的物体叫做光源，下列物体属于光源的是（　　）

有长度分别为3cm，5cm，7cm，9cm的四条线段，从中任取三条线段能够组成三角形的概率是（   ）