The president is often awakened by a noisy crowd which assembles on the White House.
【正确答案】 D
【答案解析】解析:题干:总统经常被聚在白宫的喧闹的人群吵醒。assemble的意思是“集合,聚集”,D与之最为匹配。concentrate集中,常指记忆力集中等;assume假设,认为;involve涉及,卷入。故答案为D。