They took the train to Nanjing 画线部分是 took the train

They took the train to Nanjing 画线部分是 took the train
(对画线部分提问)
_____ _______ they go to Nanjing?
Mr Smith goes to the factory by bus every day .画线部分是 by bus
(对画线部分提问)
_________ __________ Mr Smith ______ go to the factory every day
开始第一个问题本来我写的是how do
用how are
也不对,请再介绍用复数时HOW怎么用,还能用DO在后面?

1.How,did 才对.
你用how do 错在时态不对.原句动词是took,是一般过去时,所以提问时也要用一般过去时.do的过去式是did.
how are 更不对,原句中并无系动词.英语中,句子有了实意动词go,就不能再用系动词.
How does,go
此句有every day,表明句子是一般现在时,且主语是Mr Smith ,是第三人称单数,故要用does.