1）介词at, in跟on不只表示地点，也表示时光。如：Many tourists come here in autumn. They usually come in Julyand in August.很多游览者夏天到这里来。他们常在7、8月来。还可能用approximately, about, around, round, round about等词与介词连用来描述近似的时光不雅点。如：The accident happened at approximately 6:00 a.m.变乱大年夜概产生在凌晨6点。