其实是不定式省to,英语中有这样的规定,前面出现do的
话,后面的不定式可省to
What you need to do at present is (to)overcome all difficulties and convince others of your ability to finish this task.
不定式作表语.
现在你需要做的是克服所有困难,让别人相信你有能力完成这个任务