第一节：单项填空(共20小题；每小题1分，满分20分)
1. His disappearance(失踪)______ by the police.
A. looked at B. will be looked in C. is being looked into D. has been looked up
2. Her teacher helped her so much that she bought him a beautiful pen _________.
A. by turns B. in return C. in answer D. in turn
