The tree was bleeding from several points in the main trunk.这棵树主干上有好几处在流液汁。These speeches form the spine of his election campaign.这些演讲构成了他竞选活动的主干。They discovered a partially digested mouse in the trunk of one of their carnivorous plants.他们在一棵食肉植物的主干里，发现了一只已部分消化的老鼠。