
and用于肯定陈述句中。or用于否定和疑问句中。
andconj.和;与;同;又;而;加;
orconj.(用以引出另一种可能性)或,或者,还是;(用于否定句,提出两种或多种事物时)也不;(用于警告或忠告)否则,不然
Do you want one or two?
你要一个还是两个?
The operation could prolong his life by two or three years.
这次手术可使他多活两三年。
The project wasted a considerable amount of time and money.
那项工程耗费了相当多的时间和资金。