句型转换。

1. The fossils were found by a group of scientists. (对线部分媾问)

             were the fossils found         ？

2. They poured the dirty water into the lake nearby. (改为被动句)

   The                              into the lake nearby                .

3. Mom added some salt. (改为被动句)

                              by mom.

4. Meimei was worried and the librarian was worried too. (改为同义句)

   Meimei was worried and                 the librarian.

5. I heard a piece of beautiful music when I came in. (改为同义句)

    A piece of beautiful music                 my ears when I       .

简述园艺作物基因工程育种的主要技术环节？