We shouldn't ____________ litter on the ground. A. throwsB. throwC. threw
The children ran away. _____ I cried.A. so B. Then
Chinese people invented paper _____printing.A. and B. but
Yesterday I ______ my room.A. clean B. cleaned
Thank you _______ your letter.A. for B. to
A: Happy birthday to you! B:______A.OK! B. Thank you !