Obligation: have to, have got to, must
Ex. 1-Obligation with
have to
Ex. 2- Obligation with have got to: present and future time
Ex. 3-Obligation with
have to
: negative sentences
Ex. 4-Obligation with
have to
: questions
Ex. 5-Obligation in Past Time with
had to
Ex. 6-Obligation in Past Time with
had to
-negative
Ex. 7-Obligation in Past Time with
had to
-questions
Ex. 8- Obligation with must