The students _______ busily when Miss Brown went to get a book she _______ in the office.
See the model ship ____in the pool? That’s what my father made for me last weekend.
Though I was tired out that evening, I _____ from falling asleep by the great pain in my knee.
Simon was _____ why many of his friends didn’t turn up at his birthday party.
Without gravity, we _____ walk on the ground as freely as we do now.
Zhang Heng, one of _____ best-known Chinese astronomers, showed a strong interest in _____ astronomy as a child.