16. _______ dusk, the traffic often becomes heavy.
A. On B. In C. At D. For
17. —Who called just now, Sam?
—It’s Terry. She asked _____.
A. that Alice was in B. if was Alice in C. if Alice was in D. whether was Alice in
18. Since he has gone _______ a lot of hardship, he looks older than his real age.
A. over B. out C. on D. through
