A. invader B. unfortunately C. clarify D. attend A. ours B. lost and found box C. indicate D. enquiry A. swap B. be strict with C. wait for D. gray A. apart from B. square C. establish D. eagle eye A. uniquely B. by car C. investigation D. seek A. investigate B. fill with sth C. settler D. length A. consist B. concern C. construct D. hold up A. secret B. catch up C. loop D. punchline A. thousands of B. seismometer C. tipster D. infect A. foresee B. luckily C. partridge D. background