Democrats in the House of Represenatives have been pushing for vice-President Mike Pence
to invoke the 25th Amendment against President Trump.
为何是push for sb to do sth, 而不是push sb to do sth 呢？
1 《韦氏高阶》push
[no object] : to make a strong, continuous effort to get or do something — often + for
The workers are pushing hard for higher wages.
— often followed by to + verb
Town residents are pushing to prevent the shopping mall from being built.
2 《牛津》push
[transitive] to persuade or encourage somebody to do something that they may not want to do
push somebody to do something No one pushed you to take the job, did they?
从以上词典的解释和使用方法大家可以了解，push既能够用作不及物动词，后接不定式短语作目的状语；也可以用作复合及物动词，后接复合宾语，不定式短语作宾语补足语。
push for sb to do sth. push为不及物动词，意为主语作出努力，目的是让某人做某事。譬如主语可能向你的老板施压，让老板赞同你去做某事。
push sb to do sth中，push为及物动词，主语直接劝说宾语，让宾语做某事。
二个结构的意义不同，不可以互换。
网友的句子中push 为不及物动词，for sb to do sth为不定式复合结构作目的状语。
了解了这二种不一样的使用方法，网友就不会再去问为何是A使用方法 而不是B使用方法。给网友的建议：遇见类似状况，你该做的事就是查词典，查动词的使用方法，然后依据词典例句领会动词的意义。
