Ⅰ.判断下列句式的类型。
1．It was at midnight that I got back home yesterday.________
2．It was midnight when I got back home yesterday.________
3．It was the room where the important meeting was once held.________
4．It was in the room that the important meeting was once held.________
5．It was on October 1st, 1949 that the PRC was found.________
