利用维生素C能使淀粉­碘溶液褪色的性质，通过实验(如图)比较加入苹果汁和橙汁的多少来确定它们中维生素C含量的多少。要得出正确结论，在实验时需要控制的条件是(　　)

①实验时必须向两烧杯中同时滴加液体　②淀粉­碘溶液的体积和浓度必须相等　③胶头滴管滴出的果汁的滴数必须相等　④胶头滴管滴出的每滴果汁的体积必须相等

把下面的图片与所给的描述对号入座。
A        B          C 
D                E
____ He is of medium height and build, with two small eyes. He is a pop singer. And he likes playing basketball very much. He is very popular with young people.
____ He is short and of medium build. He has short black hair. He is a funny actor.
____ She is heavy. She has short brown hair. She always wears glasses. She sings very well.
____ He is very tall and has short black hair. He is a basketball player, and he plays it very well. Now he is a college student in Shanghai Jiaotong University.
____ She is thin, with long black hair and big eyes. She is a movie star. She is in the play "Palace", and she is very popular with young people.