1. David's mother asked him to water the plants. David watered the plants and then watched TV.
ANSWER: David's mother asked him to water the plants. watered and then watched TV.

2. The students mopped the floor. The students mopped the floor for ten minutes.
ANSWER: The students mopped the floor. mopped for ten minutes.

3. The girl is singing a song. The girl is happy because the song is her favourite.
ANSWER: The girl is singing a song. is happy because is her favourite.

4. Jacky bought Sam a sandwich. Sam thanked Jacky for the sandwich.
ANSWER: Jacky bought Sam a sandwich. thanked for .

5. Tom and I went to buy fruit for our mother. Tom and I bought some apples for our mother.
ANSWER: Tom and I went to buy fruit for our mother. bought some apples for .