Truly - (CW) The word translated as "truly" means "there and then," "straightway," "then," "next," "mark you!," "for this cause," "so true is it that," and "namely." It is a particle marking a sudden change or explaining or drawing attention to a consequence of an action. It is used in questions that expect a negative answer. With the objective negative, it expects a positive answer.

ye -- This is from the second-person, plural form of the verb.

bear  -- The verb "bear" here is the common form of "to be" in Greek. It means to have a certain characteristic or remain in a certain condition. It also equates terms or assigns characteristics.  The word also means "to exist" and where it doesn't connect to characteristics or conditions. However, in the KJV source, it was the verb form of the following noun, "witness." 
 

witness - -"Witness" is   the source of our word 'martyr', which means "witness." Jesus used this form only here, but he use the female form in a numer of other verses.

that -- (WW) The Greek word translated as "that" is used as the conjunction "and," but it also is used to add emphasis, "even," "also," and "just." This word doesn't mean "that." 

ye -- This is from the second-person, plural form of the verb.

allow  -- The Greek verb translated as "allow" means "join in approving", "give one's consent", "consent or agree to", and  "agree or sympathize with". The form of "the deeds" indicates the meaning is "you agree with". 

the -- The word translated as "the" is the Greek definite article, "the," which usually precedes a noun or changes the word it precedes (adjective, infinitive, participle, etc.) to act like a noun. The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," "those") than the English "the." See this article for more. 

deeds -- The Greek word translated as "deeds" means "deeds," "actions," and "things" in the sense of "every thing."

of -- This word "of"  comes from the genitive case of the following word that requires the addition of a preposition in English.  The most common is the "of" of possession.

your -- The word translated as "your" is a plural, second-person pronoun in the possessive (genitive) case. This pronoun follows the noun so the possessive "of yours."

missing "those"  -- (MW) The untranslated word is the Greek definite article, "those," which usually precedes a noun or changes the word it precedes (adjective, infinitive, participle, etc.) to act like a noun. The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," and "those"). See this article for more. 

fathers: -- "Fathesr" is the Greek noun that means "father" or any male ancestor so "forefathers." It is the word that Christ uses to address his own Father.

for -- The word translated as "for" introduces a statement of fact or cause, "for what," "because," "since," "seeing that," "that," and "wherefore." Jesus usually uses this word to mean "because" in statements that seem like an answer to a question because of the change of context. It means "because" when answering a "why" question and "that" when explaining a "what" question.

they-- This is from the third-person, plural form of the verb.

missing "themselves" -- (MW)   "Themselves" is the nominative case of the third-person, plural adjective that means "themselves," "ourselves,""yourselves," "the same," "one's true self," and "the soul" as opposed to the body. While other forms of this word are used as pronouns, this form is used for emphasis, since the subject pronoun is part of the verb. Without a verb, the sense is "they are." --

indeed -- The "indeed" here is a particle, which, when used alone, expresses certainty, "truly" and "certainly." Alone in a question, it assumes the answer like "I take it" or "isn't it."  However, when used with the conjunction translated here as "but" takes on the meaning "on one hand..." with the "on the other hand" identified by the "but" phrase.

killed -- "Killed" is translated from a Greek word that means "slaughter" more than just "kill" because the base word means "slay." The Greek source has the sense of "kill off," that is, "killing" in a more thorough way. When we talk about "slaughtering" someone, we use it to mean destroying their reputation, the strength of their spirit and ideas as well as physically killing them. This is more the sense here. The word "destroy" also works, but a similar word from a different root meaning "kill" works better as "destroy,"

them.-- The word translated as "them" is the Greek word commonly translated as third-person pronouns in English in the form of a plural object of a verb or preposition.

and -- (WW) The Greek word translated as "and" means "but," "however," and "on the other hand." It joins phrases in an adversarial way. Since it always falls in the second position, translating it as "however" often captures its feeling better. This word doesn't mean "and." 

ye -- The pronoun "you" is used explicitly as the subject of the sentence. When it has no verb, the verb "is" or the previous verb is assumed. When it is already part of the verb, its use here creates emphasis on the "you" as we might say "you yourselves." It sometimes precedes a verbal adjective or infinitive where it is not part of the verb. It is plural.

missing "yourselves"  ---- (MW) The pronoun is used here explicitly as the subject of the sentence. Since this information is already in the verb, the sense is repetitive as we say "you yourselves." 

build --- "Build" is a word that specifically means "build a house," generally, "build," "fashion," "found upon," and, metaphorically, "build up," and "edify." The English word "construct" may come closest.

their sepulchres. -- (OS) There is nothing in the Greek that can be translated as this in the source we use today but it does exist in the source that the KJV translators used.