Page 65 - Demo

See the following example.
2. グリーンさんが行っていた小学校は、次のかどにあるはずですよ。 [V]
3. 8月の日本は、かなりあついはずですよ。 [A] あんぜん
4. 大学のキャンパスは、安全なはずですよ。 [NA] 5. ルイスさんは、ジョージ・ワシントン大学の二年生のはずですよ。 [N]
When the speaker believes that something has already happened, though unconfirmed, the past form is used before はずだ・はずです as in (2).
6. 田中さんのひこうきは、一時間前にケネディ空港に着いたはずだから、もうす ぐ電話があるでしょう。
Mr. Tanaka’s flight is supposed to have arrived at Kennedy airport an hour ago, so we will get a phone call from him soon.
はずだった・はずでした (the past form of はずだ・はずです), on the other hand, describes what was supposed to have been the case, but didn’t turn out to be that way.
7. 昨日、先生と会うはずでしたが、先生はいらっしゃいませんでした。 I was supposed to meet the teacher, but s/he wasn’t there.
When you combine the past form with はずだった・はずでした, the translation should be “X was supposed to have been the case.”
8. 山下さんが行ったはずだったけど、行っていなかった。 Mr. Yamashita was supposed to have gone, but he hadn’t gone.
Here is the summary:
Non-past はずだ Past はずだ Non-past はずだった Past はずだった
It is supposed to be the case that X will happen...
It is supposed to be the case that X happened...
It was supposed to be the case that X would happen... It was supposed to be that case that X had happened...
Note: you cannot use this pattern for events that the subject feels committed to. In those cases, a different pattern, ことになっている ‘it has been arranged/agreed that X’ is used.
9. このクラスでは日本語で話すことになっている。
Lesson 14A Page 441