Printing model can't stick to hot bed

The nozzle is too far away from hot bed; please adjust the distance between hot bed and nozzle, keep the distance being a A4 paper.
The temperature of hot bed is too high or too low. When the filament is ABS, the temperature setting should be 110 degrees Celsius; when the filament is PLA, the temperature setting should be 70 degrees Celsius.
Filament problem, please replace filament supplier to adapt.
Please paste the high-temperature tape on hot bed when printing PLA/ABS filament.