181. through, across
through穿越空间，across在…上穿过 through the forest, across the desert
182. on the way, in the way
on the way在前往…的路上，in the way挡路 The chair is in the way.
183. above, on, over
above在上面，不接触，on在上面，接触，over在正上方 fly over the hill
184. until, not…until
until到…为止， not…until直到…才（常跟点动词连用）I waited until 3:00. He didn't come until 3:00.
185. besides, except, except for
besides除了…还（包括在内）except除了（不包括在内），except for整体…除了某一点以外 The composition is good except for a few spelling mistakes.
186. weather, if
当是否解时，只有在宾语从句中二者可以互换，其余都用weather，当如果解时用if I don't know if/whether he will come. If he comes, I'll let you know.
187. and, or
and并且，or或者，否则，常用于否定句中 I don't like apples or bananas.
Hurry up and you'll catch the bus. Hurry up or you'll miss the bus.
188. because, since, as, for
原因由强到弱为：because, since/as, for. 在句中的位置如下：1)…because… 2) Since/as…, … 3) …, for… Since I was ill, I didn't go.
189. when, as, while (表时间)
when从句动词点动词，持续性动词均可，as重在表示动作同时发生，伴随进行，while从句动词为持续性动词 While I slept, a thief broke in.
190. the same…as, the same…that
the same…as和…一样的（相似但不同一）， the same…that 同一物体 This is the same pen that I used yesterday. (同一支笔)
