--What’s the matter with your mother? ---She ______ a sore throat. 　　  

— Everyone should help save the planet. — Yeah. I’ve stopped ______ plastic bags when shopping. 

—Where is your dictionary, John?—Oh, I _______ it to David yesterday. He’ll return it tomorrow.

— Today the forests are getting fewer and fewer, — We must ____ down too many trees

 I must get to school before 8 am.