391. improvement in 表示原物有改进,好转

390. improve in (=get better) 有改进, 好些

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

388.under the impression that有..的印象,认为

387. make (leave) an impression on sb. =give sb. an impression 给…留下印象

386. impress…on 给…留下印象

385. impose…on 把…强加给

384. (an) impact (on) 对…的强烈影响

383. be ignorant of ( = lacking knowledge) 对…不了解,不知道

382. in ignorance of 不知道…