I may strengthen you may strengthen he may strengthen we may strengthen you may strengthen they may strengthen
V-ing form
I may be strengthening you may be strengthening he may be strengthening we may be strengthening you may be strengthening they may be strengthening
Perfect
I may have strengthened you may have strengthened he may have strengthened we may have strengthened you may have strengthened they may have strengthened
V-ing perfect
I may have been strengthening you may have been strengthening he may have been strengthening we may have been strengthening you may have been strengthening they may have been strengthening
Negation
Simple form
I mayn't strengthen you mayn't strengthen he mayn't strengthen we mayn't strengthen you mayn't strengthen they mayn't strengthen
V-ing form
I mayn't be strengthening you mayn't be strengthening he mayn't be strengthening we mayn't be strengthening you mayn't be strengthening they mayn't be strengthening
Perfect
I mayn't have strengthened you mayn't have strengthened he mayn't have strengthened we mayn't have strengthened you mayn't have strengthened they mayn't have strengthened
V-ing perfect
I mayn't have been strengthening you mayn't have been strengthening he mayn't have been strengthening we mayn't have been strengthening you mayn't have been strengthening they mayn't have been strengthening
Interrogative form
Simple form
may I strengthen? may you strengthen? may he strengthen? may we strengthen? may you strengthen? may they strengthen?
V-ing form
may I be strengthening? may you be strengthening? may he be strengthening? may we be strengthening? may you be strengthening? may they be strengthening?
Perfect
may I have strengthened? may you have strengthened? may he have strengthened? may we have strengthened? may you have strengthened? may they have strengthened?
V-ing perfect
may I have been strengthening? may you have been strengthening? may he have been strengthening? may we have been strengthening? may you have been strengthening? may they have been strengthening?
Interro-negative form
Simple form
mayn't I strengthen? mayn't you strengthen? mayn't he strengthen? mayn't we strengthen? mayn't you strengthen? mayn't they strengthen?
V-ing form
mayn't I be strengthening? mayn't you be strengthening? mayn't he be strengthening? mayn't we be strengthening? mayn't you be strengthening? mayn't they be strengthening?
Perfect
mayn't I have strengthened? mayn't you have strengthened? mayn't he have strengthened? mayn't we have strengthened? mayn't you have strengthened? mayn't they have strengthened?
V-ing perfect
mayn't I have been strengthening? mayn't you have been strengthening? mayn't he have been strengthening? mayn't we have been strengthening? mayn't you have been strengthening? mayn't they have been strengthening?