3. They last ate fish a year ago
→ It is a year since they last ate fish.
→ The last time they ate fish was a year ago.
→ They haven't eaten fish for a year.

4. It last rained eight months ago
→ It is eight months since it last rained.
→ The last time it rained was eight months ago.
→ It hasn't rained for eight months.

5. It last snowed six weeks ago
→ It is six weeks since it last snowed.
→ The last time it snowed was six weeks ago.
→ It hasn't snowed for six weeks.

6. The last time Tom cried was an hour ago
→ It is an hour since Tom last cried.
→ Tom last cried an hour ago.
→ Tom hasn't cried for an hour.