`16)` She hasn’t had a swim for five years
`⇒ ` She last had a swim 5 years ago
`@` Công thức: S+last+V(Simple past tense)
`15)` He has not written to me since April.
`⇒`The last time he wrote to me was in April.
`@` Công thức: The last time + S + V(Simple past tense)