...一类句子:He is doubtful (as
to) what we could do.张道真的意思可以用He is in doubt (as to) what we could do代替。这引出2个问题:(1) He is doubtful (as to) what we could do.这个句子句法清楚,按照现代语法进行成分划分,一般就把(as to) what we could do看...
...以暂不作类比。但是,词典有keep on + 其他介词的用法,可以参考。例如:(8)If he doesn't agree, just keep on at him
until he does. 他不答应,你就跟他磨。《新英汉大辞典》(9)I'll do it—just don't keep on at me about
it! 我会做的——可别再...