이게 맞아요?

[KleinAng]

우리 10살 때 결혼하자<<<is this correct?

or I have to add the 을?

우리 10살을 때 결혼하자<<<이게?

coz in beginner season 3 lesson 8, it says u need to add either ㄹ/을 때, 하지만
in beginner season 4 lesson 3 the sentence 우리 10살 때 결혼하자 didnt have ㄹ/을 in it,
and 살 is year right?

so isit alright to omit the ㄹ/을 sometime?

[trutherous]

을/를 is an object particle - this means the preceding word receives the action

In your example "우리 10살 때 결혼하자" '살' refers to age and it does not seem to me that it would receive the action in this sentence.
What could receive action in this sentence is '결혼' as in 결혼을 하자 but in this case the particle seems unnecessary.

There are times when object particles are dropped in conversation and when objects are followed closely by a form of "to do"

By the way, 10 seems a little young to be getting married

--anyway I am a fellow student here, my name is George, perhaps Julia or one of the other teachers will elaborate on this question.

[KleinAng]

but ㄹ/을때 is the grammar, that the problem.

Its a grammar but the ㄹ/을 is not in the sentence..

anyone can help out?

[trutherous]

I think I misunderstood your question at first. In these cases the 을 particle is not an object particle but seems to function as causing the preceding word or words to describe the following word or phrase in the sense of time.

(Lets have these two get married when they are 30 ok?)

우리 30살 됐을 때 결혼하자 Let's get married when we turn 30

대학 다녔을 때 배웠어요 - I learned it while attending college.

대학(college) 다녔다(attended) 때(time/season) now add 을, 대학 다녔을 때 and attended college now describes the time or season, e.g. 'when I attended college' or you could think of the preposition "at" and apply it this way 'AT the time I attended college.'

Here are some other examples, and a complicated Korean dictionary explanation that even my Korean born-and-educated wife shook her head at and went back to the kitchen (honest):

http://krdic.naver.com/detail.nhn?docid=30059300

Last thought: Don't stress over these little conjunctive particles, just do lots and lots of drills until you absorb it. Even many Koreans cannot explain these but they know what they mean and how they are used.

On the stairway of language one may not fully understand step 3 until one reaches step 50. Keep climbing.

It sure would be great to hear some others weigh in on this

[julialim]

[noun(time)] + 때 ; 20살 때 결혼 하자!
[verb] + ㄹ/을 때 ; 20살이 됐을 때 결혼 하자!
=20살 될 때 결혼 하자!
=20살이 되면 결혼 하자!

가다--> 가+ㄹ+때
집에 갈 때 엄마를 만났다.; I met my mom while going back home.
(on the way;the progressive tense)

----------------------<<I met my mom>>--------------------> 집


갔다--> 갔+(으)ㄹ + 때
집에 갔을 때 엄마를 만났다. ; I met my mom when I went back home.
(at home; the perfect tense)
-----------------------------------------------------> <<I met my mom>> 집

Examples of " [noun] + 때 "
점심 때 / 생일 때 / 수업 때
점심 때 뭐 먹을까? / 작년 제 생일 때(는) 미역국 못 먹었어요. /
수업 때 졸지 말아야지!

[trutherous]

Julia you are so good! Thanks!