87.我到家时，我妈妈正忙着做晚饭。

When I got home, my mother ________ ________ ________ dinner.　

根据汉语意思用英语完成句子，将答案写在横线上。

86.别担心。他会准时到来。

Don’t worry. He will arrive here ________ ________.

76.　　　　 　77.　　　　 　78.　　　　 　79.　　 　　　　80.　　　　 　　

70. The two phones are both nice. I really don’t know which one is b____ 70.　　　　

69. His teacher didn’t go home u________ all his students left school.　 69.　　　　

68. At that time my mother learned English by l　　　　 　to the tape.　 68.