nearly all trees contain a mix of polymers that can burn like petrolem ----- properly
extracted.
A after
B if
C when it
D is
ETS给的答案是D 高人给分析下这个句子谢谢
我怎么觉得A好呢省略了it is?
is在这里作谁的谓语呢?petrolem??like不能引导丛句呀!
extracted的对象是什么呢?应该是a mix of polymers吧作者: ppp1 时间: 2004-10-5 14:08