I am marking some translation exercises from Arabic into English, and I am having problem with one of the sentences. Now the sentence literally means "Malaysia will find itself overwhelmed if it decides to run the investigation on its own"*1. One of the students said "Malaysia will find itself overwhelmed if it decides to run a single investigation"*2. For me, I think the student's sentence means one investigation which makes it wrong, but I need a second opinion, does it have the same meaning as the first sentence?
"Running the investigation on its own means" that they would run the current investigation without any outside help. Seen as the investigation as very large, it might indeed overwhelm them.
The student's suggestion would indicate that Malaysia will get overwhelmed if they would run any investigation. So we are not talking about the current search for the missing air plane, but we are now stating that Malaysia incapable of, say, investigating a car-theft on their own. I doubt that conveys the original meaning :)
"On their own" means without any help, and is adverbial to running the investigation.
"Single" means "just one" and is an adjective to investigation.
The proposed change completely alters the meaning of the sentence.
Compare to these sentences:
I did this assignment on my own.
I did this single assignment.
The first one means I received no help, the second one means I did not do any other assignments.
I could even say
I did this single assignment on my own.
Meaning that for other assignments I might have received help.
Single can simply not replace on their own, it is grammatically a completely different part of the sentence :)