A:Fe2+和Cu2+
B:Fe3+
C:Cu2+
D:Fe2+
根据句意及首字母提示完成单词We went to a summer c____ last year.There w____ many trees on the mountains five years ago(以前).We are studying hard for e____ .—He was an English teacher.—R____ ? Did he teach you?What an a____ classroom! It’s too dirty!