Jack _____ leave _____ his teacher comes back. [ ]

Don’t put the bag _______ on the ground. The things in the bag are easily broken.

Eight hundred and eighty-eight million, eight hundred and eighty-eight thousand, eight hundred and eighty-eight is _________.

My backpack is made _____ leather, and it’s made _____ Yiwu, Zhejiang.[ ]

They have been doing morning exercises they up.