I'm not mistaken Rio de Janeiro of Brazil was chosen as the host city for the Olympi

问题补充：

Im not mistaken, Rio de Janeiro of Brazil was chosen as the host city for the Olympics.

A. If

B. As

C. Unless

D. Though

答案：

(答案→)A. If

B. As

C. Unless

D. Though

解析：A. If 如果B. As当…时候，作为 C. Unless除非 D. Though尽管；句意：如果我没有弄错，巴西的里约热内卢将在举办奥林匹克运动会。故选A