问题补充：
parents were at the news that their child had been injured哪个填terrified或terrifying,第一个空在were的后面，第二个在the后面
答案：
parents were (terrified ) at the （terrifying ) news that their child had been injured
父母们对他们孩子被伤害的可怕的消息感到很害怕/惊慌.
terrified 修饰人,人作主语.
adj.很害怕的,极度惊慌的,吓坏了的
另外：terrifying 修饰物.
======以下答案可供参考======
供参考答案1:
填terrified，父母看到关于他们孩子受伤的新闻后被吓坏了。
供参考答案2:
terrified 自己感到害怕,某人对什么感到害怕，主语是人,这里的主语是人，所以用这个
Parents were terrified
terrifying:令人感到害怕,某物本身所具有的…
大概意思应该是 父母听到孩子们受伤的消息很害怕
供参考答案3:
terrified
父母们对他们孩子被伤害的消息很担心
