MODEL AUXILIARY VERB (HELPING VERB)
CAN, COULD, MAY, MIGHT, WILL, SHALL, WOULD, SHOULD, MUST, OUGH TO, HAVE TO, NEED, DARE, USED TO (DESCRIBING MOOD)
• CAN/COULD (ABILITY, POWER, CAPACITY)
• ABLE TO (ABILITY, POWER, CAPACITY) IN FUTURE
DON’T USE BOTH IN ONE SENTENCE
CAN I BORROW YOUR PEN? (INFORMAL) (REQUEST/PERMISSION)
COULD/WOULD I BORROW YOUR PEN? (FORMAL) (REQUEST/PERMISSION)
CAN USED FRO PROHIBITION, ORDER, OFFER
CAN USED FOR GENERAL/FACT
COULD USED FOR LESS POSSIBILITY/SUGGESTION
COULD HAVE FOR ACTION NOT DONE
• MAY (MORE POSSIBILITY) , MIGHT (LESS POSSIBILITY)
NOT USED WITH POSSIBLY/LIKELY
MAY (PERMISSION IN FORMAL SENSE/WISH/PRAYER)
MAY + SUBJECT
• SO THAT (PURPOSE) + MAY (POSSIBILITY)
• MAY/MIGHT HAVE (PAST POSSIBILITY)
• CAN/COULD/MAY/MIGHT/WILL/SHALL/WOULD/SHOULD/MUST, OUGHT TO, HAVE TO + V1/BE
WILL (I, WE), SHALL (YOU, HE, SHE, IT, THEY)
• WILL/SHALL (PROMISE/THREAT/DETERMINATION/COMPULSION)
• SHALL (INTERROGATION)
• WOULD (PAST) (PREFERENCE…. RATHER THAN)
• WOULD (IMAGINARY SITUATION)
• SHOULD (SUGGESTION WITH FORCE/IN PLACE OF IF, DUTY, OBLIGATION)
• LEST (IN SENSE OF OTHERWISE, - IVE)
• SHOULD (NOT HAPPEN)
• MUST (NECESSITY, COMPULSION, DUTY, ORDER, DETERMINATION)
TRICK – ANYHOW
·        
OUGHT TO (GIVE KNOWLEDGE TO
OTHER)
OUGHT TO + HAVE,
OUGTH NOT TO + HAVE
·        
HAVE/HAS/HAD +
INFINITIVE (TO + V1)
·        
USED TO (PAST HABITUAL
ACTIONS), (IN PLACE OF WOULD)
·        
USED TO (AS ADJ.) (BE + USED TO
+ GERUND/NOUN)
IS/AM/ARE/WAS/WERE – BE
·        
DID + USE TO, USED NOT TO
·        
NEED + INFINITIVE, NEED NOT {NEED
NOT TO (INCORRECT)}
·        
DARE (CHALLENGE /COURAGE)
[SAME AS NEED]