[masaegu]

Originally Posted by Maxful

Thanks masaegu san. My ex-先生 said that I would be wrong if I altered 1, 2, 3 to 4, 5, 6. I do not know why though.

Strange. These are something that generally doesn't take a native speaker a second to judge. Our ears can tell instantly even before we consult our brain, so to speak. We simply cannot afford to think a minute every time we must choose between these shortest words when we must use each of them 200 times everyday.

Anyway, am I right to say that I should say "昔の日本の絵がフランスで発見されました" and "国際会議がこの町で開かれます" if the topics are discussed for the first time?

Definitely yes because it's news for everyone.