Father is too tired today. Don’t call him ________ it is necessary.
句意：爸爸今天太累了。除非有必要，否则不要给他打电话。
考查连词。A. if如果；B. unless除非；C. when什么时候；D. whether是否。根据上文Father is too tired today可知，父亲太累了，所以除非很有必要，否则不要给他打电话。B选项符合句意，故选B。
Father is too tired today. Don’t call him ________ it is necessary.
I will volunteer for a two-day home stay for an exchange student from the UK. I consider it a good chance to show Chinese food________our kindness.
—I heard a young fireman lost his life in the big fire.
—What a pity! ________I don't know who he is, I know who he is for. He is our hero forever.
We were not good friends ________we saw each other, but gradually, we got along better and better.
— It’s said that Zhou Jielun will hold a concert next month in Xiangyang.
— I’m sure the fans will be happy _______ it’s true.
We will never see Kobe play another basketball game, ________we will always remember him.
It's not easy to change habits, ______ with strong will and self-control, it is possible.
She says that she'll have to close the restaurant ______ business improves.
The boy is not very tall, _______ he runs very fast.
You will feel cold _______ you don't wear a coat.
