阅读下面材料，在空白处填入适当的内容(1个单词)。
1．It never occurred to me________ she could complete the task in such a short time.
2．The last time we had a great time was ________ we were visiting the Water Park.
3．Whether the flight to New York will be delayed is ________I'm especially worried about.
4．________ surprised the family most was ________ the girl played basketball very well.
