We must keep our classroom______.

A. cleaning         B. clean            C. to clean

We must keep our classroom______.

1. A.
   cleaning
2. B.
   clean
3. C.
   to clean

We must keep our classroom ________．

1. A.
   cleaner and tidy
2. B.
   clean and tidy
3. C.
   clean and tidier
4. D.
   cleaner and tidier

We must keep our classroom______.
A. cleaning         B. clean            C. to clean