We decided to (ask?) some students about why they go there and why do you go to the mall. As usual l go to the mall brcause my friends hang out there, but I prefer being outside; because there are a lot of free concerts there. And l also like to look at books in the bookstore, in spite of when l go into stores l always spend too much money.
我们打算调查一些学生平时为什么会去一些特定的地方,以及为什么去购物中心.一般我去购物中心都是为了陪朋友,我自己更喜欢呆在户外,因为那里总有些街边艺人的“免费音乐会”.我也喜欢逛书店,尽管每次一进去总免不了破费.
P.S.因为您这里没有指明具体要求,是所有句子整合一段还是两三句的组合,以及整合所要符合怎样的要求.所以以上我的整合有些地方尚需您说明后修改.