题目

Maria and Lisa were best friends. They shared a two-bedroom apartment in Hollywood. Maria was a clerk at a clothing store, and Lisa was a clerk at a supermarket. Their hours varied, so they didn’t get to spend a whole lot of time together. But last weekend both were off work. “Let’s go to the beach,” suggested Maria. “That’s a good idea,” agreed Lisa. “Which one?” “Well, I would prefer an uncrowded beach, because I think I’ve put on a few pounds recently. I don’t want any boys seeing my fat.” “Oh, please,” said Lisa. “You eat so little. Ounces don’t 过氧乙酸（CH3COOOH）是一种广泛、高效的消毒剂，是预防非典型肺炎的首选产品．过氧乙酸中碳、氢、氧三种元素的质量比为    ；某同学需要配制l120g 0.2%的过氧乙酸溶液，需要20%的过氧乙酸    mL（此种过氧乙酸的密度为1.12g/cm3）．