1. present
   1. perfect
      1. simple
         1. active
         2. passive
      2. continuous
         1. active
         2. passive
   2. continuous
      1. active
      2. passive
   3. simple
      1. active
      2. passive
2. future
   1. simple
      1. planned
         1. active
         2. passive
      2. unplanned
         1. active
         2. passive
   2. continuous
   3. perfect
      1. simple
         1. active
         2. passive
      2. continuous
3. past
   1. simple
      1. active
      2. passive
   2. continous
      1. active
      2. passive
   3. perfect
      1. simple
         1. active
         2. passive
      2. continuous
         1. active
         2. passive
4. conditionals
   1. zero(certain)
   2. first(likely)
   3. second(likely)
   4. third(impossible)
5. modals
   1. present
      1. will
      2. shall
      3. can
      4. may
      5. must
   2. past
      1. would
      2. should
      3. could
      4. might