Good pencils erasers are soft enough not to damage paper they crumble gradually when used. A. but hard enough so that B. and enough hard that C. and they are so hard that D. so ha
Good pencils erasers are soft enough not to damage paper _____ they crumble gradually when used.
A. but hard enough so that
B. and enough hard that
C. and they are so hard that
D. so hard are they