329. go into force 开始生效

328. (be) in force 有效 , 实施

327. be fond of 喜欢

326. focus on (=concentrate on) 集中在…上 focus sth. on 把…集中在…上

325. (be) fit for (=right and suitable for) 适合

324. fit in with ( = suit , fall into agreement) 合适, 相配, 一致

323. fit into 刚好放入

322. in the first place 首先, 第一

321. for the first time 第一次 (作状语)

320. at first sight(=when first seen)乍一看,一见