1. “Flat” 作形容词用，可以表示 “水平的，平坦的”。
This table is flat.
This bungalow (美[ˈbʌŋɡəloʊ]英[ˈbʌŋɡəˌləʊ]n.平房) has a flat roof.
2. “Flat” 作副词用，可以表示 “水平地”。
This book is lying flat.
I have to lie flat on my belly (美[ˈbeli]英['beli]n.腹部；肚子) after hurting my back.
3. “Flat” 作形容词用，可以表示 “缺乏热情的，平淡的”。我们可以用 “feel flat” 表示某人 “无精打采；感到无聊；情绪低迷”。
I feel flat because my phone doesn't work.
She left me feeling flat with her harsh (美[hɑrʃ]英[hɑː(r)ʃ]adj.严厉的；恶劣的) words.
I think the story of that movie was flat.
4. “Flat” 作名词用，可以表示 “公寓，单元房”，相当于 “apartment”。
I live in a flat in London.
He'd rather live in a house than a flat.
5. “Flat” 作副词用，放在一段时间后，可以表示 “刚刚好，正好”。
You can drive to my house in five minutes flat.
He cooks pancakes in a minute flat.
