请选择ABCD+U4];M+_7S9L(V,VThe students ____ their classroom every day.7?)v/c/`+W3b9w.i;G:b-h
A. clean7?)v/c/`+W3b9w.i;G:b-h
B. is cleaning7?)v/c/`+W3b9w.i;G:b-h
C. are cleaning7?)v/c/`+W3b9w.i;G:b-h
D. cleans7?)v/c/`+W3b9w.i;G:b-h