将下列主动语态变成被动语态。 1. We must finish the work in two days. The work must _____ in two days. 2. Mrs. Green has given Robert a present for Christmas. Robert _____ a present for Christmas. 3. We have used paper and printing for ages. Paper and printing _____ for ages. 4. He doesn't think computers can replace books. He doesn't think books _____ by computers. 5. We have bought some gifts for the poor children. Some gifts _____ for the poor children. |