How to say since you say so, i think i must believe it. in Japanese
1)
あなたがそういうのだからno dictionary result, likely a conjigated verbno dictionary result, likely a conjigated verb、、(、) Japanese comma私私(watashi) (pn,adj-no) i/meはは(ha) (int) indicating a subject/yes/indeed/well/ha!/what?/huh?/sighそれそれ(sore) (int)(n) there!/thatをを(wo) (prt) indicates direct object of action/indicates subject of causative expression/indicates an area traversed/indicates time over which action takes place/indicates point of departure or separation of action/indicates object of desire, like, hate,信じno dictionary result, likely a conjigated verbno dictionary result, likely a conjigated verbなければならないなければならない(nakerebanaranai) (exp) have to do/must/should/ought to。。(。) Japanese period "."
