No. If you want to say " ''I saw your girlfriend last night'', you have to use “看见” in context. Neither 看 nor 见 can express what "saw" mean here. If you use 看，the sentence would mean "I looked at your girlfriend last night", and if you use见，it would mean "I met your girlfriend last night."

Although both 看 and 见 can be translated into "ver" "olhar" as portuguese, in Chinese there are many habitual usages of them and some are uninterchangeable. But it is really difficult to make a summary. You'd better accumulate more sentences with using them.

Generally speaking, 看：tends to the action. 见：tends to the result, it is often used for description. 看见：is often used in formal situation when you speaking.

我昨晚看到你女朋友了 我昨晚见到你女朋友了 我昨晚看见你女朋友了