选择疑问句是要用or连接的.Would you like tea or coffee?要茶还是咖啡?
但是,否定句不一定把and变成or.or是指任一一种,而and指两者同时.
Did you buy bread or butter?你要买面包呢?还是买黄油?
Did you buy bread and butter?你要买黄油和面包吗?更可能是：你要买黄油面包吗?
Do you have brothers or sisters?你有哥哥或者是姐姐吗?
Do you have brothers and sisters?你哥哥姐姐都（同时）有吗?
仔细体会吧.