ROBERT ... FOR MARY SINCE NOON.A. IS GOING TO WAITB. HAS BEEN WAIT...

31. - 3500 CAU TRAC NGHIEM ON TAP AV THCS
3500 CAU TRAC NGHIEM ON TAP AV THCS

31. Robert ... for Mary since noon.

a. is going to wait

b. has been waiting

c. is waiting

d. was going to wait

-> b