一个英语句子看不懂语法

题目

一个英语句子看不懂语法
he accepted their mistaken estimate of his ability, felt that is was useless to try,and was very poor at arithmetic, just as they expected. 特别是felt that is was useless to try看不懂,请帮忙分析一下结构.谢谢

答案

不好意思,前几天只是看了一眼问题就匆匆回复了,回答的有些草率.
但我说此句引导词"that"后面缺主语并没有问题.只不过当时没有注意LZ多打了一个"Be"动词.为什么说"that"后面缺主语,因为"felt"后面是"that"引导的宾语从句,引导词"that"在宾语从句中不作任何成分,也无任何意义,只起引导词的作用,所以that后面必缺主语成分
此句涉及到并列句中的省略问题:
语法规则:在并列句中,相同的成分如主语,谓语,宾语等都可以省略：
此句因为有两个以上的并列关系子句,所以把并列连词"and"放到了最后.
三个并列句中的谓语"accepted,felt,was" ,由于他们的主语相同都是"He"
为避免重复,后两个省略掉了.
对于LZ的问题补充:"felt that "主语" was useless to try"
此句只是省略主语"He"的并列句.如果让此句做状语,那应该把"felt"改成
"feeling"
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