有A、B、C三种元素，A元素是地壳中含量最多的元素，B元素形成的一种氧化物是导致酸雨的主要气体，C元素是用途最广的金属．
按要求填空：
（1）A元素的名称______；
（2）B元素形成的导致酸雨的氧化物的化学式______；
（3）C元素形成的一种合金的名称______；
（4）A、B、C三种元素形成的一种化合物的化学式______．
（1）地壳中含量最多的元素是氧元素，所以A是氧元素，故填：氧．
（2）B元素可以是硫，形成的氧化物是二氧化硫．故填：SO2．
（3）用途最广的金属是铁，所以C是铁元素．铁的合金有钢和生铁．故填：生铁．
（4）氧元素、硫元素、铁元素可以形成硫酸亚铁．故填：FeSO4
| 完形填空。阅读下面短文，掌握其大意，然后从各小题所给的四个选项中选出最佳选项。 | ||||
| Miss Joan was a kindergarten (幼儿园) teacher who taught in a small village school. She always worked long hours to prepare interesting 1 for her students. She also helped the other teachers, giving them many good 2 to help them teach better. She loved her students and they loved her, too. Yes, in many ways she was nearly perfect. 3 , she did have two small shortcomings (缺点). First, she would always 4 snacks in her desk. Sometimes the food attracted mice and other unwanted guests. Her the other shortcoming was that she was 5 afraid of snakes. She would not allow anyone in her class to 6 pictures of snakes or even say the word. She was even afraid when her kids were 7 about words that start with the letter S. One day these two things came 8 . A teacher 9 knew about Miss Joan's two shortcomings decided to make fun of her. He bought a toy snake in a shop. When Miss Joan wasn't in the classroom, he took away some of her snacks and put the toy snake 10 her desk instead. When Miss Joan took out the snack to eat, she saw a toy snake. She was too frightened to move, and from then on she never hide snacks in her desk. | ||||
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