begun

[notletrest]

[FONT=&#23435]The research is so designed that once--begun --nothing can be done to change it. a.begins b. begun [/FONT]​

[FONT=&#23435]Why we can say The meeting began at five.But we cann't "the research begins?Thanks a lot![/FONT]​

 

[Frank Antonson]

[FONT=&#23435]The research is so designed that once--begun --nothing can be done to change it. a.begins b. begun [/FONT]
[FONT=&#23435]Why we can say The meeting began at five.But we cann't "the research begins?Thanks a lot![/FONT]​

"Begun" is the past participle. If it helps to insert the works "it has", do that. The sentence would be okay if it read, "The research is so designed that once it begins nothing can be done to change it."