I can alert you can alert she can alert we can alert you can alert they can alert
V-ing form
I can be alerting you can be alerting she can be alerting we can be alerting you can be alerting they can be alerting
Perfect
I can have alerted you can have alerted she can have alerted we can have alerted you can have alerted they can have alerted
V-ing perfect
I can have been alerting you can have been alerting she can have been alerting we can have been alerting you can have been alerting they can have been alerting
Negation
Simple form
I cannot alert you cannot alert she cannot alert we cannot alert you cannot alert they cannot alert
V-ing form
I cannot be alerting you cannot be alerting she cannot be alerting we cannot be alerting you cannot be alerting they cannot be alerting
Perfect
I cannot have alerted you cannot have alerted she cannot have alerted we cannot have alerted you cannot have alerted they cannot have alerted
V-ing perfect
I cannot have been alerting you cannot have been alerting she cannot have been alerting we cannot have been alerting you cannot have been alerting they cannot have been alerting
Interrogative form
Simple form
can I alert? can you alert? can she alert? can we alert? can you alert? can they alert?
V-ing form
can I be alerting? can you be alerting? can she be alerting? can we be alerting? can you be alerting? can they be alerting?
Perfect
can I have alerted? can you have alerted? can she have alerted? can we have alerted? can you have alerted? can they have alerted?
V-ing perfect
can I have been alerting? can you have been alerting? can she have been alerting? can we have been alerting? can you have been alerting? can they have been alerting?
Interro-negative form
Simple form
can I not alert? can you not alert? can she not alert? can we not alert? can you not alert? can they not alert?
V-ing form
can I not be alerting? can you not be alerting? can she not be alerting? can we not be alerting? can you not be alerting? can they not be alerting?
Perfect
can I not have alerted? can you not have alerted? can she not have alerted? can we not have alerted? can you not have alerted? can they not have alerted?
V-ing perfect
can I not have been alerting? can you not have been alerting? can she not have been alerting? can we not have been alerting? can you not have been alerting? can they not have been alerting?