it occur to sb that的否定形式：
it doesn't/didn't occur to sb that，根据句子occur的时态选择；
疑问句形式：
Does/Did it occur to sb that，根据occur的时态选择；
1. that后面主语从句的时态和occur保持一致；如果是occurs，那么后面可以是现在时，也可以是过去式；
2. 如果是occurred，那么后面就是过去时。
3. 分析：
it occur to sb that的汉语翻译：
某人突然想到。
结构分析：
it，形式主语；
occur to动词词组作谓语；
sb，是宾语；
that，引导真正的主语从句。
举例说明：
It occurs to me that I forgot to lock the door!
我突然想起我忘记锁门了！
否定句：It doesn't occur to me that I forgot to lock the door!
一般疑问句：Does it occur to you that I forgot to lock the door？
It occurred to me that she expected a response.
我这才意识到她在期待我的回答。
否定句：It didn't occur to me that she expected a response.
一般疑问句：Did it occur to you that she expected a response？