根据短文理解，从A、B、C、D搜歌四个选项中选择正确答案。

      Mrs. Li and Grandma were going to Los Angeles, USA that Sunday to see Uncle Mike. He 1 in Los Angeles for six years.

      Mrs. Li and Grandma had never been to another country. They planned to stay in Los Angeles for two weeks. They would not come back 2 the end of the month.

     They had bought their air tickets already. They had done a lot of things, but not 3. They had not packed their suitcases 4. Grandma had bought Uncle Mike many presents. She had bought 5 T-shirts and several paintings. She had also bought some tea and dried mushrooms.

    “Have you got enough space in your suitcase?” asked Mrs. Li.

    “Yes, because I've only got a small amount of tea, not 6.” said Grandma.

    “How about the dried mushrooms? How many packets have you got?” asked Mrs. Li.

    “I've got 7 packets, not too many. Don't worry, my dear” replied Grandma.

    “But I can't help8.  I haven't got enough room in my suitcase.” Said Mrs. Li.

    “If so, you can put some of your things in my suitcase. My suitcase is larger than 9.” said Grandma.

      Then Mrs. Li put part of her things into Grandma's suitcase and they left 10.

某电动机的工作效率是83%，从能量转化看，它表示电动机工作时（　　）