flu flu 是 influ 是 更 厉害
flu flu 是 influ 是 更 厉害 .
WORD_BOUNDARY WORD_BOUNDARY 
f l u WORD_BOUNDARY f l u WORD_BOUNDARY 是 WORD_BOUNDARY i n f l u WORD_BOUNDARY 是 WORD_BOUNDARY 更 WORD_BOUNDARY 厉 害 WORD_BOUNDARY