题目

阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。 When seven­year­old Sky Nockels learned that black rhinoceroses (犀牛) were an endangered species, he decided to do something to help them. He raised money to adopt (收养) a black rhino named Imara at the Great Plains Zoo in South Dakota. By adopting Imara, Sky helps the zoo take care of the rhino's needs, such as food and a good habitat. Sky has been a summer camp member at the Great Plains Zoo since he was three. There he and other kids learnt about the animals and did projects for them. 对化学方程式2H2+O2 点燃 . 2H20表示的意义，下列叙述正确的是（　　）A．氢气加氧气等于水B．在这个反应中，H2、O2和H20的质量比为2：32：18C．两个氢分子跟一个氧分子在点燃的条件下就等于两个水分子D．氢气和氧气在点燃的条件下反应生成水