21.【2019 •河南省】—Shall I help you go         the street, Grandpa?
   —No, thanks. I can manage it myself.
   A. on B. with C. across D. along
【答案】C
【解析】句意：——爷爷，我帮你过街好吗？——不，谢谢。但我自己能行。A. on在……上；B. with和……在一起；C. across横过；D. along沿着。根据Shall I help you        the street, Grandpa? 我帮你_______ 好吗？可知，应该选择across横过；across the street：穿过街道。故选C。