节日，特别是黄金周期间增长的客流主要是民工和学生流。
参考答案：错
绒癌为一种（）度恶性肿瘤，较（）会发生（）转移到全身。
________scores of times, but Derek still couldn’t understand how to use past participle in a concrete situation.
A．Having explained
B．Having been explained
C．Though it was explained
D．It was explained
