管理人员从一池塘内捞出30条鱼，做上标记后放回池塘。10天后，又从池塘内捞出50条鱼，其中有标记的有2条。根据以上数据可以估计该池塘内共有（ ）条鱼。
750
据下列句子及所给汉语注释，在句子后边的横线上，写出空缺处各单词的正确形式。（每空只写一词）
1. Mike's family used to live in a _______(欧洲的) country.
2. There are no _______ (钢琴) in the school for the poor children to play.
3. Don't be frightened by the television camera. Just speak _______(自然地).
4. The doctor told me to have more _______(蔬菜) and fruit.
5. A great celebration was held on his ________(50岁) birthday.
6. Talking of his father's death, she kept on _______(擦拭) her eyes with a handkerchief.
7. He will come here next _______(八月).
8. He _______(未能) to pass the driving test last summer.
9. The monitor forgot _______(提醒) us about the time and place for the meeting.
10. My friend was so _______, so we drove to a shopping mall to get some food.
期货交易在多数情况下要进行实物交收，只有少数是在合约到期前进行反向交易、平仓了结。（）
