题干
Last time, he offered to do my homework for me , but I ____________.
A：refused
B：refuse
C：have refused
D：will refuse
答案(点此获取答案解析）
A
Last time, he offered to do my homework for me , but I ____________.
A：refused
B：refuse
C：have refused
D：will refuse
表示一种原子，用 
表示另一种原子，有如图化学反应，则下列说法中错误的是（ ） 