Can you help me combining these sensor sketches as one in Arduino
Variable renaming

Rename thresholdValue in the first two sketches to rainSensorThreshold, and lightSensorThreshold respectively, and sensorThres to smokeSensorThreshold in the third sketch.

Rename sensorValue in the first two sketches to rainSensorValue, and lightSensorValue respectively, and analogSensor to smokeSensorValue in the third sketch.


Change the Analog pin
Use A1 (or some other analog input other than A0 or A5) for ldrPin in the second sketch, for example:
int ldrPin = A0;

Consistant LED pins
Use the same pins in the third sketch, as are used in the first two sketches, for the two LEDs and note the change in case:
int greenLed = 11;
int redLed = 12;

to
int greenLED = 6;
int redLED = 7;

Recompile each sketch
To check that the each sketch still works, recompile each one separately.
Combine the code
Finally... Splice the code together appropriately, keeping the three parts separate:

Global variables
setup()
loop()