One of the instructors gave/did a demonstration of how to prune a tree.一位指导者演示了如何修剪树木。The instructor demonstrated the correct procedure for pruning a tree.指导者演示了修剪树木的正确步骤。I've been put in the position of being the conductor of this defense and I have to lead.我被放到了这场辩护的指导者位置上，因此我不得不领导全局。