将下列句子改为同义句：1、whose is that backpack
____ does that backpack ____ ____
2、The young people will have fun at the picnic .
The young people will ____ ____ at the picnic .
3、Can you hear that someone is singing outside
Can you hear ____ ___ outside
4、Do you know who the blue car belong to
Do you know ____ the blue car ____
5、Maybe there is somthing strange in the sky .
There ____ ____ something strange in the sky .
6、The girl seemed to be worried .
____ ____ that the girl ____ worried.