Tom works very hard at his lessons.He did not get the first in the exam.

题目

Tom works very hard at his lessons.He did not get the first in the exam.
A.however B yet C.though D although

答案

but 是连词,连接两个并列句,中间用逗号隔开.表示转折
如：I wanted to buy a book,but I don't have enough money.
though 是副词,但在句中的成分相当于连词.引导从句,不能与but 连用,可以放句首或者句中.意思是尽管,though 和although不可以与but连用,
1.(al)though 是从属连词连接一个从句,but是并列连词连接一个并列句,一个句子要么是主从句要么是并列句,所以两者不可能出现在同一个句子中,只能单个使用：
Although it was expensive,we decided to buy the computer.=The computer was expensive,but we decided to buy it.
2.however语气比but强,但由于同样的理由不能与(al)though 出现在同一个句子中.
如：Though it is so hot I have to go outside.
I have to go outside though it is so hot.
however 也是副词,剧中成分相当于连词.可以放在句首或句中,后面一定要用逗号.表转折.放句首时,与前面的句子是转折的连接.放句首时,前后用逗号隔开
如：I wanted to buy a book,however,i do not have enough money.
区别：①although和though同义,在一般情况下,可以互换使用.只是though较普遍,常用于非正式的口语或书面语中,而although则较为正式.另外although语气比though重,常用以强调让步概念.
e.g.Though/Although my car is very old,I don't want to buy a new one.
虽然我的汽车很旧,但我不想买一辆新的.
He insisted on doing it although I warned him not to.
虽然我警告他不要做,但他仍然坚持要做.
②even能和though组合表示强调,但even不能和although组合.因此,不能说even although,在这里even though=even if(no matter if; though即使……也……)
e.g.Even if/Even though we could afford it,we wouldn't go abroad for our vocation.
即使我们付得起这笔钱,也不出国度假.
③当让步状语从句指某种假设情况时,通常用though,而不用although.
e.g.Though all the world were against me,I should still hold to my opinion.
就算全世界都反对我,我还是坚持我的立场.
Though everybody deserts you,I will not.
即使所有人都抛弃你,我也不会的.
④though可以独立用作副词,常放在句末,意为all the same (还是；仍然)或however(可是；然而),而although无此用法.
e.g.She didn't tell me what she had done,but I know it though.
她没有告诉我她所做的事情,但我还是知道了.
It's hard work.I enjoy it,though.
工作很苦,可是我喜欢.
⑤though引导让步状语从句时可以倒装,而although从句则不能.
e.g.Bravely though they fought,they had no chance of winning.
虽然他们打得很勇敢,但还是没有机会获胜.
相同点：①在although和though引导的让步状语从句中,主句里不可用but,若要强调前后两部分的对比意义,可在主句前加yet或still.
e.g.Although/Though he has a lot of money,yet/still he is unhappy.
他虽然有很多钱,但并不幸福.
②although和though引导让步状语从句时,常采用省略形式.
e.g.Although tired (=Although he was tired),he kept on working.
虽然很疲劳,但他继续工作.
The problem,though complicated(=though it is complicated),can be solved without much difficulty.