题目内容：

i lost my bike,and i really don't know _____.A what should i do B what to do C how shall i do

优质解答

选择B
what与do连用 how与deal连用 故排除C
I don't know ...是主谓宾结构 know为谓语 后接宾语 应该是名词 what.其后的to do是what的后置定语（to+不定式做后置定语）