Regular verb: lack - lacked - lacked
Simple form | V-ing form |
I must lack you must lack she must lack we must lack you must lack they must lack | I must be lacking you must be lacking she must be lacking we must be lacking you must be lacking they must be lacking |
Perfect | V-ing perfect |
I must have lacked you must have lacked she must have lacked we must have lacked you must have lacked they must have lacked | I must have been lacking you must have been lacking she must have been lacking we must have been lacking you must have been lacking they must have been lacking |
Simple form | V-ing form |
I mustn't lack you mustn't lack she mustn't lack we mustn't lack you mustn't lack they mustn't lack | I mustn't be lacking you mustn't be lacking she mustn't be lacking we mustn't be lacking you mustn't be lacking they mustn't be lacking |
Perfect | V-ing perfect |
I mustn't have lacked you mustn't have lacked she mustn't have lacked we mustn't have lacked you mustn't have lacked they mustn't have lacked | I mustn't have been lacking you mustn't have been lacking she mustn't have been lacking we mustn't have been lacking you mustn't have been lacking they mustn't have been lacking |
Simple form | V-ing form |
must I lack? must you lack? must she lack? must we lack? must you lack? must they lack? | must I be lacking? must you be lacking? must she be lacking? must we be lacking? must you be lacking? must they be lacking? |
Perfect | V-ing perfect |
must I have lacked? must you have lacked? must she have lacked? must we have lacked? must you have lacked? must they have lacked? | must I have been lacking? must you have been lacking? must she have been lacking? must we have been lacking? must you have been lacking? must they have been lacking? |
Simple form | V-ing form |
mustn't I lack? mustn't you lack? mustn't she lack? mustn't we lack? mustn't you lack? mustn't they lack? | mustn't I be lacking? mustn't you be lacking? mustn't she be lacking? mustn't we be lacking? mustn't you be lacking? mustn't they be lacking? |
Perfect | V-ing perfect |
mustn't I have lacked? mustn't you have lacked? mustn't she have lacked? mustn't we have lacked? mustn't you have lacked? mustn't they have lacked? | mustn't I have been lacking? mustn't you have been lacking? mustn't she have been lacking? mustn't we have been lacking? mustn't you have been lacking? mustn't they have been lacking? |