21. The teacher divided class __into______four groups.
22. He provide us __with______a lot of useful information.
23. The ground is covered __with______trash. You should clear __up______all the trash.
24. Raw sewage is pumped directly ___to_____the sea.
25. They are trying to save the animals _from_______extinction.
26. The world will end _up_______like a second-hand junk-yard.
27. I am looking forward ____to____hearing from you.
28. Don’t throw trash __into______the water