Just as they were about to sit down and eat, __(一阵震耳欲聋的尖叫声)__ reached their ears.

(a)  

A wave of panic swept through May and her mother as they noticed that a boy was struggling to __(保持漂浮)__.

(a)  

May's father. who was calm, __(立刻；马上)__ dived into the water and saved the drowning boy.

(a)  

As soon as they came ashore, May's mother wrapped a towel around the __(正发抖的；正颤抖的)__ boy.

(a)  

The boy's parents were __(感激到没有言语可形容)__ and.....

(a)  

...they thanked May's father for his __(敏捷的举动和及时的帮助)__

(a)