(1) He struggled pertinaciously for the new resolution.

(2) The image of an impending calamity is no doubt odious, but its very odiousness makes it haunt the mind all the more pertinaciously, and it is useless to expel it.

(3) The image of an impending calamity is no doubt odious, but its very odiousness (we say) makes it haunt the mind all the more pertinaciously, and it is useless to expel it.

(4) So she began to walk slowly after him, in the direction he had gone, slowly, pertinaciously.

(5) Perhaps one day I will realize, in fact what I am fighting pertinaciously all my life, is just for Godat.