write + should
kaku hazu da
should; ought to; is supposed to
meaning: is supposed to write
あいつなら答えを知ってるはずだよ。
aitsu nara kotae o shitteru hazu da yo.
If it's him, he should know the answer. casual
荷物は今日の午後に届くはずだ。
nimotsu wa kyou no gogo ni todoku hazu da.
The package is supposed to arrive this afternoon. neutral