Based on the researches of relevant studies and investigation of linguistic data at different times, the generation mode of the verb phrases(VP) of “〖WTBX〗unavoidable〖WTBZ〗” and “〖WTBX〗hard to avoid〖WTBZ〗” are deduced, analyzed and generated from the perspectives of Xbar Theory and Government Theory. The study shows that “〖WTBX〗unavoidable〖WTBZ〗” indicates the certainty and high probability of occurence, while “〖WTBX〗hard to avoid〖WTBZ〗” means the difficulity of avoiding something happening. Thus, there are no similarities between “〖WTBX〗unavoidable〖WTBZ〗” and “〖WTBX〗hard to avoid〖WTBZ〗” in phrasal aspect, because the two VPs play different roles in specific pragmatics shifting from notional word to function word.