$6.$ It’s nearly five years since my brother last saw his best friend.
$→$ My brother hasn’t seen his best friend for nearly five years.

$*$ Công thức : It's + thời gian + since + S + last + V(quá khứ).

$=$ S + have/has + not + V3 + for + khoảng thời gian/since + thời gian được xác định.
$7.$ It started to rain at 2 o’clock.
$→$ It has rained since 2 o'clock.

$*$ Công thức : S + started/began + V_ing + thời gian.

$=$ S + have/has + V3 + for + khoảng thời gian/since + thời gian được xác định.
$8.$ It started to rain an hour ago.
$→$ It has rained for an hour.

$*$ Công thức : S + started/began + V_ing + thời gian.

$=$ S + have/has + V3 + for + khoảng thời gian/since + thời gian được xác định.

$9.$ When did you begin to learn English?
$→$ How long have you learned English ?

$*$ Công thức : When + did + S + V_nguyên thể ?

$=$ How long + have/has + S + V3 ?
$10.$ The last time I saw him was in 1985.
$→$ I haven’t seen him since in 1985.

$*$ Công thức : The last time + S + V_quá khứ + was + thời gian.

$=$ S + have/has + not + V3 + for + khoảng thời gian/since + thời gian được xác định.

$#Mei UwU$