1.

$\text{1.}$ When I was ten, I began playing football.

$\text{→}$ began/ started + V-ing

$\text{2.}$ In the future, my father will go abroad.

$\text{→}$ In the future ⇒ TLD

$\text{3.}$ Reading books in my free time is my favourite hobby.

$\text{→}$ V ở đầu câu thường thêm -ing

$\text{4.}$ I think skating is more interesting than mountain - climbing.

$\text{→}$ think + N/ V-ing + is + adj

$\text{5.}$ I don't know why my mother likes cooking.

$\text{→}$ like + V-ing

$\text{6.}$ He will collect books whenever he has money.

$\text{→}$ whenever: bất cứ khi nào

$\text{7.}$ How many paintings has she painted?

$\text{8.}$ I love flowers, so I plant them around my house.