1) I'm sorry for (not) (calling) you these days.
2) Nobody likes (being) (laughted) at. ※laught at 人　人を笑う → [受動態]人 [be laughted] at　人は笑われる
3) My sister is proud of [(having) (studied)](動名詞・完了形) at this high school.

参考にしてください。