The streets are bedecked with red banners.

街旗招展。

Red flags stand out brightly, set against the blue sky.

旗在蓝天的映衬下显得分外鲜艳。

The streets are decked with a sea of red flags.

街道旗的海洋。

Red flags flow in the east wind.

旗在东风中飘扬。

The walls have been draped with red banners.

用旗将墙装饰起来了。