问题
选择题
None of us was good at swimming, so the crossing of this dangerous river was really a_________.
A．motivation
B．symptom
C．conflict
D．challenge
答案
答案：D
考查名词辨析：A．motivation动机B．symptom症状C．conflict 冲突D．challenge挑战，句意：我们没有人擅长游泳，所以过这条危险的河真是挑战。选D。