at the exhibition在展覽會in the exhibition在展覽中 during 一般指在展會期間如：the exhibition period參展期間on就用得比較少，一般是看它的主語，或者之前的動(dòng)詞有與on連用的。如：pictures on the exhibition展覽會的畫像The Exhibition on Hakka Folk Art客家民間藝術(shù)展演活動(dòng)He appreciates the xx at DCBA 2009 Beijing.