并列句句子成分的划分,要先从并列连词——如but,and,so,or,yet——处分开,然后再对前后分句进行句子成分分析.例如：
It is 6:00 o'clock in the afternoon, but they haven't finished their work yet.
这一并列句是由but连接的,分析句子成分时要将but前后的两个分句各自进行分析.
It（主语） is（系动词） 6:00 o'clock（表语） in the afternoon（状语或是定语）这一句是“主——系——表”结构；
they（主语） haven't finished（谓语） their work（宾语） yet（状语）.这一句是“主——谓——宾”结构.
如果分句是复合句,则需要逐层进行分析.如：
It is 6:00 o'clock in the afternoon, but they haven't finished their work which was assigned them yesterday.
在 they haven't finished their work which was assigned them yesterday.这个分句中,又包含着which was assigned them yesterday.这样一个定语从句,它应属于第二层了.
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