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Mark: Has NASA observed the phenomenon?

Olivia: According to NASA, these observations have _______ a challenge to the scientific community.

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Jacob: We don’t allow _______ in the pool. The pool is used for photo shooting only.

Ella: What a pity! We will leave right away.

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Ethan: Why is the bowl removable?

Chloe: The bowl is removable _______ cleaning.

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Sophia: It is believed that low-fat biscuits are a healthy _______ to cakes.

David: Yes, you can buy low-fat biscuits for your kids instead of traditional biscuits.

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Noah: Remember to tell your brother the news.

Grace: _______ he ring, I will tell him the news.

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Daniel: His public speaking skills improved a lot.

Hannah: He devoted himself _______ his public speaking skills.

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Mason: Do you have any requirements for the bride and bridesmaid’s looks?

Isabella: Both the bride and bridesmaid’s looks should work hand _______ hand to complement each other.

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Emma: Do you know how Coca Cola was invented?

Jack: Yes. John first tried to cure headaches with a _______ of cola leaves and cola nuts.