In my Chinese lesson, I learnt “我去美国出差一个星期” (present tense) as the duration comes after the verb, but when I said “我去美国出了差一个星期” (past tense), my teacher said it was wrong and corrected my sentence to “我去美国出了一个星期的差”, so the duration is in the middle of the sentence.
The best article that I looked for an explanation this one about time durations and I know 出差 is a separable verb, so I have to put the object 差 at the end of the sentence (as according to Pattern 2). But this still confuses me, as “我去美国出差一个星期” is still correct.
Can anybody help me clear up the confusion? Is “我看书五分钟” correct or do I need to correct the sentence to “我看五分钟的书”, where 看书 is obviously not a separable verb?
EDIT: For future reference, I've had a look at "Modern Mandarin Chinese Grammar" (1st edition) by Claudia Ross and Jing-heng Sheng Ma and found another pattern in Section 35.1.2.
You can also use verb + object + verb (了) + time duration, examples from the text:
我每天晚上看书看四个小时。 - Every night I read (books) for four hours.
You can add 了 after the second verb if you are referring to the past:
我睡觉睡了八个钟头 - I slept for eight hours.
This doesn't affect the premise of my question, but this structure is also good to know.
EDIT 2: It seems the crux of the matter is whether 出差 is a verb-object phrase, in which you need to place the object after the duration, or whether 出差 can be considered a verb in the whole, as per user2249675's answer, and so the duration goes after the verb. I'm happy for the moment that 出差 can be used as both, but in which scenarios, I'll leave it for somebody to have a go at explaining.