题目

完形填空。The Read family comes to a new big city，but Mrs.Read's son，Bob，is not happy.He doesn't have anyone to play with.“ Don't__1__！”says his mother，“You will soon make friends here.”One morning，there is a __2__at the door.Bob's mother，Mrs.Read，opens it.There stands a woman with brown hair.It is Mrs.Miller.She comes to borrow some __3__．She wants to_4__cakes.Mrs.Read gives her two.In the afternoon，there is another knock at the door.Mrs.Read opens it and sees a boy__5__there.“My name is Jack Miller，”he says，“My mother sends you this cake and the two下列6个转化，其中不能通过一步反应实现的是① SiO2 → Na2SiO3 ②Fe(OH)2―→Fe(OH)3 ③ SiO2 → H2SiO3 ④ Al2O3―→Al(OH)3 ⑤ Na2O2 → NaCl ⑥NaAlO2―→AlCl3A．①② B．③④ C． ③④ ⑤ D．⑤⑥