筈(はず)expectation that something took place, will take place or was in some state, it should be so, bound to be, expected to be, must be, nock (of a bow), nock (of an arrow), nock-shaped grip (between thumb and forefinger), wooden frame on the tip of the mast of a Japanese ship that prevents the hawser from falling out

頭(あたま)がいい人(ひと)は成績(せいせき)もいい筈(はず)です。

People who are smart should also have good grades. {expectation that something took place, will take place or was in some state, it should be so, bound to be, expected to be, must be, nock (of a bow), nock (of an arrow), nock-shaped grip (between thumb and forefinger), wooden frame on the tip of the mast of a Japanese ship that prevents the hawser from falling out}

お医者(いしゃ)さんはこの病気(びょうき)の仕組(しく)みを知(し)っている筈(はず)だ。

The doctor should know the mechanism of this disease. {expectation that something took place, will take place or was in some state, it should be so, bound to be, expected to be, must be, nock (of a bow), nock (of an arrow), nock-shaped grip (between thumb and forefinger), wooden frame on the tip of the mast of a Japanese ship that prevents the hawser from falling out}

パーティー好(ず)きの彼女(かのじょ)がこのパーティーに来(こ)ない筈(はず)がない。

There's no way she, who loves parties, wouldn't come to this party. {expectation that something took place, will take place or was in some state, it should be so, bound to be, expected to be, must be, nock (of a bow), nock (of an arrow), nock-shaped grip (between thumb and forefinger), wooden frame on the tip of the mast of a Japanese ship that prevents the hawser from falling out}

その真面目(まじめ)な性格(せいかく)からして、彼(かれ)はもう学校(がっこう)に着(つ)いている筈(はず)だ。

Given his serious personality, he should have already arrived at school. {expectation that something took place, will take place or was in some state, it should be so, bound to be, expected to be, must be, nock (of a bow), nock (of an arrow), nock-shaped grip (between thumb and forefinger), wooden frame on the tip of the mast of a Japanese ship that prevents the hawser from falling out}

刑事(けいじ)：「お前(まえ)は犯行(はんこう)について何(なに)か知(し)っている筈(はず)だ！白状(はくじょう)したまえ！」

Detective: 'You are supposed to know something about the crime! Confess it!' {expectation that something took place, will take place or was in some state, it should be so, bound to be, expected to be, must be, nock (of a bow), nock (of an arrow), nock-shaped grip (between thumb and forefinger), wooden frame on the tip of the mast of a Japanese ship that prevents the hawser from falling out}