在清冰雪工作中，某驻哈武警部队出动兵力600人参加三条街路的清冰雪劳动，其中A街路清冰雪的人数占此次出动兵力总人数的$\frac{2}{5}$，余下的人参加B街路和C街路的清冰雪劳动，并且参加B街路清冰雪人数是参加A街路清冰雪人数的$\frac{3}{5}$，参加C街路清冰雪人数是参加B街路清冰雪的人数的$\frac{3}{2}$．

Today’s young people are taking a more active part in online activities. Although the Internet can be 1for students to collect information and communicate（交流）with their friends, teachers and parents are becoming more and more 2 about the unhealthy web content（网上内容）in the bar. They think that the birth of “Harm-free Internet Bars”（健康网吧）is3 step to4teenagers.
It was Sunday afternoon and there were not many 5 seats left in the Feiyu Internet Bar. A few6 were found playing 7. A person of the bar was walking around 8 Internet users’ online activities.
“My job is to find anyone who is looking at9 websites and then 10them from doing so,” he said. “This is a 11 of the ‘Harm-free Internet Bar’project”. Feiyu, a famous Internet bar in Beijing is among the first 19 to12 the harm-free Internet bar club.
In order to help start a better 13 for teenagers’ online activities, China’s Communist Youth League has brought out the program named “Harm-free Internet Bar for Teens”.
But while teachers and parents14the “harm-free Internet bars”,15 do many school students think of them?

①非极性分子中只含有非极性键        

②极性分子中只含有极性键        

③含有阳离子的晶体一定是离子晶体    

④原子晶体中一定含有非极性键

⑤实验测得气态BeCl₂为共价分子，两个Be﹣Cl键间的夹角为180°，由此可判断BeCl₂属于非极性分子           

⑥CS₂在水中的溶解度很小，是由于其属于非极性分子．

下列投影一定不会改变△ABC的形状和大小的是（　　）