One of the responsibilities of the Coast Guard is to make sure that all ships______follow traffic rules in busy harbors.
【正确答案】 B
【答案解析】dutifully“守本分地”。cautiously“小心谨慎地”；faithfully“忠诚地”；skillfully“熟练地”。要填副词修饰follow，表示老实地遵守交通规则，故选B。