答案：分别填 to cross, frightened 害怕的

即；It's easy ( to cross ) the river by boat. The little boy is ( frightened )to see the big dog.He can't move at all.

解析：cross the river 过河,be easy to do sth 容易做某事,be frightened to do sth 做某事感到害怕

翻译：坐小船过河是很容易的.这个小男孩看到这只大狗很害怕,他一动也不敢动.



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