If there is a bridge, you'd better break it first-pull some tanks and press ctri to hit the bridge.

At the same time, rebuild two or three anti-aircraft guns and some dogs to prevent enemy paratroopers. ...

No bridge; First block the intersection with soldiers and tanks to prevent the enemy from attacking. Then build a few dark tones or sentry guns that don't need electricity. Then build two money factories and satellites to detect enemy attacks early and build more carports ... haha. It's up to you now.