could meaning in Chinese

(can 的过去式)
1.〔特殊用例〕打算，要，想。 I could laugh for joy. 我高兴得想笑。 Really I could not think of it. 真的那是我不愿意考虑的。 I couldn't think of allowing it. 我没有允许的意思。 ★could 与感觉动词连用时，表示“要，想”，与一般动词连用而表示“能够”时，为避免与“要，想”混淆起见，通例不说 could 而改说 was [were] able to, 若所指行动须经过努力或会遇到困难，则通例不说 could 而改说 managed to, succeeded in -ing.例：I could do it＝I was able to do it. He could reach the top of the mountain. ＝He managed to reach [succeeded in reaching] the top of the mountain.
2.〔用于假设语气的条件句〕 if I could 〔现在〕假定可能的话(但事实上不可能)。 if I could have done so 〔过去〕假定做到了(但事实上没有做到)。
3.〔用于虚拟语气的结论句〕 I could if I would. 〔现在〕假定我要做就可以做到〔但事实上不打算做〕。I could have done it. 〔过去〕假定我本来是可以做到的〔但未做〕。