问题
选择题
how to solve the problem, the little boy turned to his father for help.
A．Not knowing
B．Having not known
C．Not having been known
D．Not known
答案
答案：A
考查现在分词的否定做状语，句意是：不知道怎么解决问题，小男孩向父亲求助。The boy和know是主动关系，not发在现在分词前面。选A。