1. Which **FOUR** of the following situations were witnessed on the
请选择 1 个答案
A. The frequency of oscillation increased after some time.
B. All the engineers went to see the ceremony that day.
C. The design of the bridge astonished the people.
D. Unexpected sideways movement of the bridge occurred.
E. Pedestrians had difficulty in walking on the deck.
F. The bridge fell down when people tried to retain their balance.