阅读下面的唐诗，完成小题。
贼平①后送人北归
司空曙
世乱同南去，时清独北还。
他乡生白发，旧国见青山。
晓月过残垒，繁星宿故关。
寒禽与衰草，处处伴愁颜。
【注】①贼平：指平定“安史之乱”。
Spring is a beautiful____ of a year. It's from March to ____. A lot of flowers come out. The weather is windy and ____. Spring is the best time to ____trees. I like spring best. ____my birthday is in April. It's on ____18th . 1 usually have a party ____that day.
（ω>0）在区间
上单调递增，在区间
上单调递减，则ω=" " 
（ ）
