Can (presente) Could (passado)

Expressa:

Capacidade: She can swim./She could swim years ago.
Permissão / Possibilidade: You can leave now.
Pedido polido: Could you leave, please?

Formas:

Afirmativa: She can swim./She could swim years ago
Negativa: You cannot (can't) leave now.
You couldn't leave during the class.
Interrogativa: Could you leave, please?
Can you speak English fluently?

Exercício

1.
HE COULDN'T RUN VERY FAST LAST YEAR, BUT NOW HE CAN. Explique o motivo de não ter sido usado CAN'T.

me ajudem pfvr​