Hebrew Alphabet
Hebrew Verbs: Hiphil
Hifil has specific prefix Hi. In the imperfect it is always letter patah under the its prefix.
Hebrew Verbs: Hitpael
Hitpael has specific prefix Hit. It has doubled middle letter in its root (dagesh), in all its forms. In the imperfect shewa is present under the prefix (under taw). Imperfect prefix letter substitutes H in Hitpael prefix.
Hebrew Verbs: Niphal
Nifal has specific prefix Ni. In the imperfect this prefix is assimilated with imperfect prefix in a way that the first letter of the root is doubled (dagesh).
Hebrew Verbs: Piel
Piel has doubled middle letter in its root (dagesh), in all its forms. In the imperfect shewa is present under the prefix.