—I’m dead tired. I can’t walk any farther, Jenny. —______, Tommy. You can do it!
( ) 28. Things fall to the ground _______ go up into the air because of gravity.
( ) 27. Take _______ half, they’re exactly the same.
( ) 26. I have been studying computer for several years and I still __________.
( ) 25. This book is said to be a special one , which _______ many events not found in other history books.
( ) 24. Electricity _________ us with light, heat and power.