那条未经训练的狗对孩子们来说是个危险。

The untrained dog is a ___danger to children.

医生警告说，吸烟对你的健康非常危险。

The doctor warns that smoking is a great ___danger to your health.

结冰的道路对行人很危险。

Icy roads are a ___danger to pedestrians.