16. —Is Doctor Green________ORBIS doctor?
—No, he is________UNICEF volunteer. But he sometimes works with ORBIS.
A. a; an B. an; a C. an; an D. a; a
17. He was born________ October, 2002.
A. in B. on C. at D. of
18. My shoes are cheaper than ________.
A. you B. your C. yours D. your one
