A good idea to him, and he knew to do next.
A. happened , what
B. appeared ,how
C. occurred ,what
D. arrived ,how
网友回答
A. happened , what
B. appeared ,how
(答案→)C. occurred ,what
D. arrived ,how
解析：happen多表示某事件突然发生,appear出现,occur,突然出现某种灵感,arrive到达,根据题意选C,他突然想起一个好主意,知道了接下来做什么.