382.in ignorance of不知道……
383.be ignorant of (=lacking knowledge)对……不了解，不知道
384.(an) impact (on)对……的强烈影响
385.impose……on把……强加给
386.impress……on给……留下印象
387.make (leave) an impression on sb. =give sb. an impression给……留下印象
388.under the impression that有……的印象，认为
389.improve sth. (make sth. better)把原物改进 improve on (=produce or be sth. better than……)另做一物比原物更好
390.improve in (=get better)有改进，好些
