imperative

a.紧急的；必要的

impeachable, impeachment, impeccable, impeccably, impecunious, impecuniously, impecuniousness, impedance, impede, impediment, impedimenta, impel, impend, impending, impenetrability, impenetrable, impenetrably, impenitence, impenitent, impenitently, imperatively, imperceptible, imperceptibly, imperfect, imperfection, imperfectly, imperial, imperialism, imperialist, imperialistic, imperially, imperil, imperious, imperiously, imperiousness, imperishable, impermanence, impermanent, impermeability, impermeable,