【单选题】________ what she meant.
A.
Only then I understood
B.
Only then I did understand
C.
Only then did I understand
D.
Only then did I understood
【单选题】Negotiators shouldn't only think about themselves.
【单选题】If only I ______my car!
【单选题】If only I _____ my watch!
【简答题】Americans aren't the only people in the world who travel.