Yesterday it [be] very cool .but tomorrow it [be] not 适当形式填空

Yesterday it [be] very cool .but tomorrow it [be] not 适当形式填空
Yesterday it [be] very cool .but tomorrow it [be] not 适当形式填空

Yesterday it [be] very cool .but tomorrow it [be] not 适当形式填空
yesterday是过去式的标志,用过去式 was
tomorrow是将来时的标志,用 will be

was
will be

it was ... will be