1. " The meeting in China were delayed by three days". In this sentence, why use " by", not " for"? - "To be delayed by [a period of time]" means that the event did not start until after that period. Using "for" sounds less natural, and implies the event started but there were then delays, e.g. "the plane was delayed for three hours" implies that everybody was on the plane, sat in the airport, and it took off three hours late. 2. " As a result, he had to change the dates for his stay in China". In this sentence, why use " for', not " of"? - Either "for" or "of" would be fine here. 3. " One reason for the trip was for business". Why use " for', not"of"? - Here, "for" means "for the purpose of", so "of" would be incorrect. 4. "This tree is bending over because of the strong wind." Why use " bending over" not just " bending"? - You could say just "bending", "bending over" is more descriptive. "Bending" could describe a small or big movement, whereas "bending over" describes a big movement. 5." It is going to be windy for the new next few days." Why use " for", not "in"? - Here, "for" means "during", so "it is going to be windy for the next few days" means "it is going to be continuously windy during the next few days." "In" means "inside" or "within", so if you say "it is going to be windy in the next few days", this means "sometime during the next few days, it is going to be windy." I hope this helps, your questions are advanced - native speakers would understand you if you use these words in the wrong place!

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