Английский язык. бональщина

Пожалуйста помогите мне с английским, все понимают эту тему а до моего бедного умишки все никак не доходит!
PRESENT PERFECT TENSE

Use the Present Perfect Continuous and for or since for each of the following situations.

Вроде как это пример:
My friend started reading an interesting book a month ago. He is still reading it. He HAS BEEN READING the book since last month.

задания. .
1. Dmitry started playing chess when he was 10 and he is still playing it.
....since he was 10
2. Victor began writing a letter to his pen-friend in the U.K last week and he is still writing it.
....since last week.
3. Omar's father started driving his car when he has 20 and he is still driving it.
....since he was 20.