句型转换。

1. My parents should allow me to study with friends.(改为同义句)

    I should ______ ______ to study with friends.

2. They oft en clean their classroom after school. (改为被动语态)

    Their classroom ______ often ______ by them after school.

3. Li Lei gave Tom a new pen last week. (改为被动语态)

    A new pen ______ ______ ______Tom last week.

4. It took him ten years to finish writing the book. (改为同义句)

    He ______ ten years ______ the book.

5. They will publish these story-books next month. (改为被动语态) 

    These story-books ______ ______ ______ next month.

天目溪，是浙江富春江的一条支流，因源出天目山而得名，又称分水江。素有“溪有18滩，一滩高一滩”之说。（　　）