If winter comes, days get shorter. You heat metal, it expands. Iron gets wet, it rusts. Do not water the plants, they die. Heat water to 100 degrees, it boils. Drop ice on water, it floats. You come, we can talk about it. They meet, they discuss all details.

Task: Complete the sentences using "if" or "unless".

• 1. Unless winter comes, days get shorter.
• 2. If you heat metal, it expands.
• 3. If iron gets wet, it rusts.
• 4. If you do not water the plants, they die.
• 5. If you heat water to 100°, it boils.
• 6. If you drop ice on water, it floats.
• 7. If you come, we can talk about it.
• 8. If they meet, they discuss all details.

Explanation: The sentences provided are already examples of conditional sentences using 'if' to describe a cause and effect relationship. The task implies rewriting them or confirming their structure. For sentence 1, 'unless' is provided as an alternative to 'if not'. The remaining sentences are straightforward conditional statements where the first clause describes the condition and the second describes the result.