128 Accidence [§§272-3 NOTE.—ι. An instrumental neut. bē-ei also occurs, but only as a conjunction, batei is also used as a conjunction. 2. Where the cases of the simple pronoun end in -a this -a is elided before the particle ei (except in the nom. sing. masc.). On the z in bizei, &c., see §§ 175 note, 261. 3. Besides the nom. sing, forms saei, sōei, there also occur forms made from the personal pronouns, thus masc. izei (from is + ei); fem. sei (from si + ei), which is more frequently met with than soei. Instead of izei the form izē occasionally occurs (cp. § 5). The form izei (izē) is sometimes also used for the nom. pi. masc.; bái sinđ bái izē, these are they who; atsaíhnb faura líugnapraúfētum þáim izei qimand at izwis, beware of false prophets, of them who come to you. Some scholars assume that sei is an indeclinable demonstrative particle representing an old locative like Latin sī, if; sīc from *sei-ke, so, thus; and that izei is from an older *e-sei (cp. Gr. ί-κεΐ, there), where e- is the pronominal stem mentioned in § 270. At a later period sei and izei came to be regarded as compounds of si + ei and is + ei. This theory has much in its favour, because it explains why sei and izei have no oblique cases and why izei is used for the masc. nom. singular and plural. § 272. The relative pronoun for the first and second persons is expressed by suffixing ei to the respective personal pronouns, thus ikei, (/) who; þuei, (thou) who; þukei, (thee) whom ; þuzei, (to thee) whom; juzei, (ye) who; dat. pi. izwizei, (to you) whom. 6. Interrogative. § 273. The parent Indg. language had two stems from which the interrogative pronoun was formed, viz. cjo- and qi- with labialized q (§§ 127,134). The former occurs in Gr. ir«5-T£pos. which of two ?, Goth, hras, OE. hwa, who ?, from an original form *qos; Lat. quod, Goth, hra, O.Icel. huat, OS. hwat, OHG. hwa;?, OE. hwæt, what?, from an original form *qod. And the latter occurs in Gr. rís,