（ ）summer，Ilike swimming with my friends．

in

时间名词前常用的介词有in,at,on三个,
in 后面常接时间段（in summer, in two hours)
at 后接确切的时间点（at midnight, at six thirty),
on 后面接具体的某一天 （on Sunday, on October 1, on Christmas),所以本题应该选 in.

in +季节

in

in

in