邻居的狗经常在后院叫。
The neighbor's dog often ___barks in the backyard.
我们的狗对任何不熟悉的声音都会叫。
Our dog ___barks at any unfamiliar noise.
当害怕时，狗可能会凶猛地叫。
When scared, a dog may ___bark aggressively.