1.理解没错.但是如果从句是客观真理,即使主句是过去时,从句还用一般现在时.The teacher told us that the earth goes areound the sun.
2.主句是现在时,从句是任意时态.也就是说从句可以是过去,将来,现在,进行等.
I don't know if he will come tomorrow.I don't know if he came yesterday.
3.Neither Jim nor Tom is a student.
两者都不,用neither...nor...,后面谓语动词就近原则,也就是和neither后面的词一致.因此用单数.neither...nor...本身就是不的意思,因此不要再加not..what does the Great Wall look like？ The kid asked his mother，这句难道从句要用过去完成时？.what does the Great Wall look like？一般现在时， 改从句为过去时。其实要改时态的话， 只要把从句的第一个动词改为过去式就可以了。 这句looks 改为looked will-would is -was have-had plays/play- played