His uncle used to be a doctor.这是动词不定式作什么成分表语还是
His goal is to be a doctor.
他的目标是当大夫。
his goal(主语) is(系动词) to be a doctor(不定式短语作表语)
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为你解答，如有帮助请采纳，
如对本题有疑问可追问，Good luck!
be动词后加“形容词、名词、介词短语、动词不定式、动名词、从句”等作表语。
如：
1、He is happy . (形容词作表语）
2、 She is a student.（名词作表语）
3、He is in a white T-shirt today.（介词短语作表语）
4、His dream is to be a doctor.（不定式短语作表语）
5、 Seeing is beliving .（动名词作表语）
6、 It seems that he is very happy . (从句作表语）
例句对照：
一、【当做主动词时，"be"在性质上属于接系动词(The Linking Verb), 后面要有名词、形容词、地方副词或短语作补足语(The Complement)。】例如:
1、The man is a science teacher.
这个男子是一位科学教师。
2、Mary's new dresses are colourful.
玛丽的新衣服色彩鲜艳。
3、I havebeen there before.
我以前去过那里。
4、My motheris in the kitchen now.
我妈妈现在在厨房里。
二、这四个都是陈述句，可以变成疑问句，方法简单，把主语和"be"或助动词对换位置即可:
1、Is the man a science teacher?
2、Are Mary's new dresses colourful?
3、Have I been there before?
4、Is mother in the kitchen now?
三、当"be"要在祈使句中出现时，陈述句可借助助动词"do"，否定句必须在前加上助动词"don't"，如:
1、Don't be silly!
2、Do be obedient!
3、Be careful!
4、Don'tbe a fool!
四、"Be"有两种缩写法，如下:
1、He's not...../He isn't....
2、You're not...../You aren't...
五、但"am + not"的缩写法只有一个:
I'm not.
六、有人用"ain't", 但这并不是标准英语。
动词不定式作表语表示还没发生的动作， 而动名词作表语表示习惯性的动作。 eg . His dream is to be a doctor . His hobby is fishing .
叶山童康： 为你解答. His uncle used to be busy.(改为否定句) His uncle (used not) to be busy. 他叔叔过去不忙. 解释:used to do,过去常常做.否定式在to do前加not.
广宗县19843796226： 汉译英 他的叔叔过去住在乡下,现在住在城里. 并用上used to - ？
叶山童康： His uncle used to live in the countryside.now he lives in the city.
广宗县19843796226： His uncle used to be a doctor.这是动词不定式作什么成分表语还是 - ？
叶山童康： used to 是情态动词,和can , may, must 一样,它的后面应该是动词原形.
广宗县19843796226： His uncle - ------(过去)be a teacher. - ？
叶山童康： used to
广宗县19843796226： His uncle used to be busy改同义句？
叶山童康： 答案是:His uncle was very busy in the past ☞ ♧手工翻译☀尊重劳动☀欢迎提问☀感谢采纳♧ ☜
广宗县19843796226： he was taught by his uncle to used his feet as hands 什么意思 - ？
叶山童康： 他被他的叔叔教会把脚当做手那样.(直译) 解释为:他叔叔教他怎样用脚可以像用手一样
广宗县19843796226： 英语句子翻译【我叔叔曾经生活在一个小村庄(used to)】[这本书如此有趣,以至于我读了三次(s - ？
叶山童康： My uncle used to live in a small village.This book is so interesting that I read it three times.I will buy a new dictionary even if I have to borrow money.We had to take a taxi to the train station yesterday in order to catch the train.My mom is reading a ...
广宗县19843796226： My uncle used to - ___ - the school volleyball team.A.in B.be at C. be on D,on - ？
叶山童康：[答案] 选C used to do sth.过去常常干什么 on the team在某个队
广宗县19843796226： His uncle - --- - (not used ) to drink. 用括号里中所给词的适当形式填空,这道题怎麽做？
叶山童康： His uncle ___doesn't used__ (not used ) to drink.
广宗县19843796226： his uncle smoked in the past,but now he does't的同义句 - ？
叶山童康： 是不是写错了...不管是一个空还是两个空,后面都应该是smoking吧?his uncle give up smoking
