orry if you don’t understand everything, the teacher will ______ the mainpoints at the end.

We climbed to the top of Dayan Pagoda at night , believe it or not, ______ we could see a Buddha image in the sky.

The boy is old enough to ________ the difference ________ right and wrong.

下列各项中，标点符号使用正确的一项是（ ）

Not until he called the secretary three times ______ that the manager went to an important meeting. [ ]