once的用法1。Theresearchissodesignedthatoncenothingcanbedonetochangeit.A.beginsB.havingbegunC.beginningD.begun2。Anarmyspokensmanstressedthatallthesoldiershadbeenorderedclearwarningsbeforef

Question

once的用法
1。
The research is so designed that once _____ nothing can be done to change it.
A.begins B.having begun C.beginning D.begun
2。
An army spokensman stressed that all the soldiers had been ordered _____ clear warnings before firing any shots.
A.to issue B.being issued C.to have issued D.to be issued
(选什么？为什么 ？请从语法角度谈，希望有专业老师讲解！！！)
请问Once引导的是什么从句？

Answer 1

我是高三老师,你说的这2题我都做过,讲过,还算专业吧这两个都是高考题1. D once引导从句,表示一旦....这里是个省略句:The research is so designed that once (it is)begun, nothing can be...一旦开始,没有什么可以...