4.  exert  v. 施加

近义表达

exert sth  on sb /sth  to do sth： bring (a quality,skill,pressure,etc) into use; apply sth.

 Eg.: His wife exerted a lot of pressure on him to change his job.

        He likes to exert his authority on us.

exert oneself 努力，尽力(不能用于被动)

Eg.: He never exerted himself to study hard.

exert/make every effort 尽一切努力

5.  subtle adj. 微妙的，难以捉摸的=hardly noticeable;敏感的，敏锐的新概念英语第二册

Eg.: Advertisements exert subtle influence on us.

       He is a subtle observer.

联想记忆

subtly adv.微妙地，敏锐地

subtleness == subtlety