Byrd at once ordered his men to throw out two sacks,这个句子里面的t

这个就是动词不定式，动词不定式就是to+动词原形，至于规律 (1）动词不定式做主语 eg: To swim with you was very enjoyable. 注：动名词和动词不定式均可以做主语和表语，但动名词表示经常性的，抽象的动作，而不定式表示特指的一次性的具体的动作。 (2）动词不定式做表语 eg: Her wish is to become a teacher. 注：表语为不定式时，主语也是不定式；当主语部分含有动词do时，做表语的不定式可以省略to. eg: To see is to believe. All you have to do is (to) study hard. (3) 不定式做宾语 以下及物动词后常用动词不定式： want,decide,aim(目标),manage(试图),hope,ask,happen,like,love,choose,prevent(阻止),promise,continue,plan,learn,fail等。 eg: I decide to look for a job. (4) 动词不定式做定语 动词不定式做定语往往要后置，与被修饰词之间存在动宾关系、主谓关系、同位关系和修饰关系。如果动词不定式是不及物动词，应该在动词后加上适当的介词。如果被修饰词是地点、时间、方法，通常省略动词不定式后的介词。 eg: I have something to say.(动宾关系） I was the last one to leave here.(主谓关系） I have no wish to quarrel with you.(同位关系） This is the best way to do that.(修饰关系） I have nothing to worry about.(不及物动词后加介词） I can't find a place to play (in).(省略介词in) 注：当名词用特定的定语如：frist,last,next,only等以及形容词最高级修饰时，后面用不定式修饰。 eg: He is the only person to know the truth. (5）不定式做状语 不定式做状语主要表达结果、目的和原因。 eg: He worked day and night to play for the debts.(目的状语） He woke up to find everyone gone.(结果状语） We laughed to hear the news.(原因状语） 注：动词不定式与only连用时，可表出乎意料的结果。 eg: He went to seaside only to be drowned. (6) 动词不定式做补语 eg: Allow me to introduce her to you.