It is two weeks since I have seen him.( have seen-- saw)

是 have seen
watch 和see‘
watch 侧重动作.是瞬间动词
see侧重结果,是延续性动词
现在完成时用的是延续性动词

这句话翻译成,我不认为以前我已经见过你穿那条裙子.现在完成时,是动作或过程发生在说话之前某个没有明确说出的过去时间现在已经完成,并与现在的情况有联系

都不对,应该是saw
我们已经是三个礼拜没见到他了

A.问题里是Have you seen,那你回复里也跟著用 have seen 就好了
如果对方问你 Did you see it?那你回答 I saw it on his bed 也可以
seen 是从 see > saw > seen 来的,

saw,just now译为刚刚

没见过这个用法，不过关于 toward 这个词汇。我在维恩词典官网上找到一个人点回答：
Which should you use, "toward" or "towards"?
Wednesday January 25th 2012
Question
Which should you use, "toward" or "towards"?
Answer
Question
Margaret from the US asked when to use toward and towards.
Answer
Although this is a question that confuses many, the answer is simple: Toward and towards are completely interchangeable, so you can use either one whenever you want.
Now let’s go a little deeper:
Toward and towards are prepositions that mean “in the direction of someone or something, or close in location or time." As prepositions, they are followed by nouns or noun phrases.
However, there is a difference in their usage. Although toward and towardsare used at about the same frequency in spoken language, in written language toward is used much more often than towards, roughly five times as often. (This applies to American English only; in British English towardsis the more common variation.) So if you'd like to be on the safe side, use toward and you won't be wrong. But the choice is really up to you.
Below are some common expressions and example sentences withtoward/towards.
attitude toward(s) Rachel has a serious attitude toward(s) her work.
to turn toward(s) The flowers will turn toward(s) the sun.
toward(s) the end of We're going on vacation toward(s) the end of the month.
I hope this helps.
http://www.***.com/qa/which-should-you-use-toward-or-towards

have seen 是以see动词的完成时态,不是固定搭配,不存在用法的问题.have+动词分词就是完成时态,表示已经完成某事.
比如 我已经写完作业了,I have finished my homework.

I saw One of the most touching pictures which I have never seen before
by chance on my friend's blog.