THEY WAITED FOR A BUS. ... THE END, THEY GAVE UP AND WALKED. A. AT...

27. - 3500 CAU TRAC NGHIEM ON TAP AV THCS
3500 CAU TRAC NGHIEM ON TAP AV THCS

27. They waited for a bus. ... the end, they gave up and walked.

a. At

b. In

c. On

d. By

 b