Future Time Clauses in a Host-Family Email
Ken is writing a short email to his host family in Fukui. He wants to say three things: (1) his flight arrives at Komatsu Airport at 3 p.m.; (2) he will call them when he arrives; (3) if it rains on Sunday, they will go to the museum instead of the park. His draft says: 'I will arrive at Komatsu Airport at 3 p.m. I call you when I will arrive. If it will rain on Sunday, we will go to the museum.' His classmate Aya says the second sentence should be 'I will call you when I arrive,' and the third should be 'If it rains on Sunday.' Ken thinks adding 'will' makes the future clearer. Their teacher asks them to explain the pattern, not just correct it. The email is due tomorrow.
1. Correct Ken's second sentence and explain the grammar rule in a way Ken can apply to other sentences.
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Corrected sentence: 'I will call you when I arrive.' The rule is about time clauses: after conjunctions such as when, after, before, as soon as, until, English uses the present simple to talk about the future, while the main clause carries will. The arrival is the future event that triggers the call, but the clause 'when I arrive' is grammatically present. Ken's 'when I will arrive' sounds like a separate question or a noun clause. A useful test: if the when-clause can be replaced by 'at the time that...', use present simple. Compare: 'I don't know when he will arrive' - here 'when he will arrive' is the object of know, a noun clause, so will is correct. In Ken's email, 'when I arrive' modifies call, so it is a time clause.
2. Correct the third sentence and explain why 'If it will rain' is wrong in this context. Then write one sentence where 'will' after 'if' is acceptable, and explain the difference.
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Corrected sentence: 'If it rains on Sunday, we will go to the museum instead of the park.' In a real future condition (first conditional), the if-clause uses the present simple and the result clause uses will. 'If it will rain' is not the standard pattern for a weather condition because will is already marking the result; the condition is treated as a present possibility. Will after if is acceptable when if means 'whether' and introduces a noun clause: 'I don't know if it will rain tomorrow.' There, 'if it will rain' is the object of know, not a condition. Another special case is a polite request: 'If you will wait a moment, I will check.' For Ken's sentence, the meaning is conditional, so 'if it rains' is the correct choice.