Употребление герундия или инфинитива (с to или без to).
Easy
Practice 1
Practice 2 (New File, Elementary)
Practice 3 (English File, Elementary)
Practice 4 (English result, Pre-Intermediate)
Practice 5 (American New File)
Medium
Practice 6
Practice 7 (English Result, Pre-Intem)
Hard
Practice 8 (New English File, Interm.)
Practice 9
Practice 10 (English Result, Interm)