Spanish cognates are a great tool for learning vocabulary. The examples below show groups of common cognates. 
There is a group of English words that end in al that do NOT change in Spanish
Examples of Spanish Cognates:
Hospital  ---> 	Hospital
Medical	  ---> Medical
Animal  ---> 	Animal
Casual  ---> 	Casual
Digital  ---> 	Digital
Final  ---> 	Final
Ideal  ---> 	Ideal
Tropical	  ---> Tropical
There is a group of English words that end in ble that do NOT change in Spanish
Examples of Spanish Cognates:
Audible  ---> 	Audible
Cabble	  ---> Cabble
Terrible  ---> 	Terrible
Destructible  ---> 	Destructible
Horrible  ---> 	Horrible
Flexible	  ---> Flexible
Impossible  ---> 	Imposible
Visible	  ---> Visible
There is a group of English words that end in ar that do NOT change in Spanish
Examples of Spanish Cognates:
Familiar	  ---> Familiar
Lunar  ---> 	Lunar
Muscular  ---> 	Muscular
Regular  ---> 	Regular
Solar  ---> 	Solar
Vulgar  ---> 	Vulgar
Similar  ---> 	Similar
Popular  ---> 	Popular
There is a group of English words that end in ment that change to mento in Spanish
Examples of Spanish Cognates:
Argument --->	Argumento
Cement  --->	Cemento
Department  ---> 	Departmento
Document  ---> 	Documento
Element  ---> 	Elemento
Ligament  ---> 	Ligamento
Moment  ---> 	Momento
Pigment  ---> 	Pigmento
There is a group of English words that end in id that change to ido in Spanish
Examples of Spanish Cognates:
Acid  ---> 	Ácido
Fluid  ---> 	Fluido
Rapid  ---> 	Rápido
Solid	  ---> Sólido
Valid	  ---> Válido
Stupid  ---> 	Estúpido
Liquid  ---> 	Líquido
Vivid	  ---> Vívido
There is a group of English words that end in ence that change to encia in Spanish
Examples of Spanish Cognates:
Coincidence  ---> 	Coincidencia
Competence	  ---> Competencia
Difference	  ---> Diferencia
Excellence  ---> 	Excelencia
Frequence  ---> 	Frecuencia
Intelligence  ---> 	Inteligencia
Presence	  ---> Presencia
Violence  ---> 	Violencia
There is a group of English words that end in ant that change to ante in Spanish
Examples of Spanish Cognates:
Abundant	  ---> Abundante
Distant	  ---> Distante
Elegant	  ---> Elegante
Important  ---> 	Importante
Mutant	  ---> Mutante
Vacant	  ---> Vacante
Tolerant	  ---> Tolerante
Instant	  ---> Instante
There is a group of English words that end in ary that change to ario in Spanish
Examples of Spanish Cognates:
Canary	  ---> Canario
Diary  ---> 	Diario
Glossary	  ---> Glossario
Estuary	  ---> Estuario
Primary	  ---> Primario
Salary	  ---> Salario
Vocabulary  ---> 	Vocabulario
Temporary	  ---> Temporario
There is a group of English words that end in ic that change to ico in Spanish
Examples of Spanish Cognates:
Alcoholic  ---> 	Alcohólico
Basic  ---> 	Básico
Fantastic  ---> 	Fantástico
Generic	  ---> Genérico
Medic  ---> 	Médico
Organic  ---> 	Orgánico
Panic	  ---> Pánico
Romantic  ---> 	Romántico
There is a group of English words that end in ance that change to ancia in Spanish
Examples of Spanish Cognates:
Ambulance  ---> 	Ambulancia
France  ---> 	Francia
Distance	  ---> Distancia
Substance  ---> 	Substancia
Tolerance	  ---> Tolerancia
Elegance  ---> 	Elegancia
Importance  ---> 	Importancia
Abundance  ---> 	Abundancia
There is a group of English words that end in ct that change to cto in Spanish
Examples of Spanish Cognates:
Act  ---> 	Acto
Exact  ---> 	Exacto
Correct  ---> 	Correcto
Insect  ---> 	Insecto
Dialect  ---> 	Dialecto
Perfect  ---> 	Perfecto
Product  ---> 	Producto
Conflict	  ---> Conflicto
There is a group of English words that end in ous that change to oso in Spanish
Examples of Spanish Cognates:
Curious  ---> 	Curioso
Delicious  ---> 	Delicioso
Glorious	  ---> Glorioso
Mysterious  ---> 	Misterioso
Numerous  ---> 	Numeroso
Precious	  ---> Precioso
Religious  ---> 	Religioso
Tedious	  ---> Tedioso