[求助]1998 08 北美

n9ga1

8 In this pure state antimony has no important uses, but ___ with other substances, it is an extremely useful metal.

(A) When combined physically or chemically

(B) combined when physically or chemically

(C) the physical and chemical combination

(D) it is combined physically and chemically

答案： A  

还是不明白

n9ga1

谢谢帮忙~~

hoiabm

以下是引用n9ga1在2005-5-27 8:15:00的发言：

8 In this pure state antimony has no important uses, but ___ with other substances, it is an extremely useful metal.

(A) When combined physically or chemically

(B) combined when physically or chemically

(C) the physical and chemical combination

(D) it is combined physically and chemically

答案： A  

还是不明白

这里是状语从句省略结构 原句应该是 but when [it was] conbined physically and chemically

相关知识点：

省略条件：

1、特定状语从句引导词：although,though,even though, if , when, while, as, whether  2、从句为主系表结构

省略方式：同时省略主语和系动词 如：when mushrooms was eaten --> when eaten

n9ga1

不是说要和主句一致 才可以省略吗？

pcpcpcpcpc

这是一个分句，but开始是另一个完整的句子，主语是后面的it，其实三个小句子的主语都一样，都是antimony.

n9ga1

谢谢~~ 帮忙~~~