How are my 用词造句 ("use the word to make a sentence") sentences using 幸福 and 俩? In the HSK4上 Standard Course workbook, the first practice exam has this problem:


  


It's a 用词造句 ("use the word to make a sentence") problem.  I came up with these sentences:


  我妹妹十一月会结婚，太幸福了！
  My younger sister will get married in November, too happy!
  
  他们俩今天在商店一起买新衣服了。
  Those two bought new clothes at the shop today.


I just made this up off the top of my head when sitting the practice exam, and I'm not sure what to think about my answer.

I'm hoping for a critique of the sentences, and possibly some comments as to if this is the kind of thing the examiners are looking for along with some techniques for these types of questions.

Question: How are my sentences?
我妹妹十一月会结婚，太
  幸福了！
  
  他们俩今天在商店一起买新衣服了。


Basically, both of your sentences are ok grammatically. The first one can be improved if you replace 会 with 要. 


  我妹妹十一月要结婚，太幸福了！


要 sounds more emotional than 会 in this context. 会 is a bit "objective", less sentimental.  In this sentence, you want to express the excitement(indicated by 太幸福了！), so 要 is fit better. It's like saying, 我妹妹要结婚了！ 太幸福了！！！