It thumps gently against the trunk of the tree.

它轻轻地撞击树干。

Tim wagged his tail and thumped it hard against her ankles.

蒂姆摇着尾巴，用力敲击她的脚踝。

They followed as fast as they could. Jack’s heavy pack thumped against his back as he ran.

他们尽可能地紧随其后。杰克沉重的背包在他奔跑时砰砰作响。