黄仁宇在《大历史不会萎缩》一书中说：“在中国地图上可以画出一条15英寸等雨线……凡线之以南以东，平均每年至少有15英寸之雨量，可堪耕作，线之以北以西，则低于此最少的雨量。而这等雨线也是胡汉之分划和少数民族及多数民族几千年长期交兵之处，而尤以气候干旱和人口过剩时为然”。对上述材料理解错误的是（    ）

    Tom and Mike had a very good time last Sunday.That morning，they1at six o'clock and dressed(穿衣)themselves.2having breakfast，they went to the park.It's in the centre of the city. In the park.there were a lot of nice flowers.Mike wanted to 3one，but Tom stopped(阻止)him.He told Mike it was not.4to pick flowers.Then they went to the lake.By the lake,they saw a small5.They jumped into it and started a tour on the lake.Two hours6,they left the lake and walked up the hill(小山)near the lake.They got to the top at half past eleven.There they had their lunch.7did they have for lunch?Eggs，bread and oranges.In the afternoon,they 8home.When their mother asked them about the morning，9answered，"It was great.We10ourselves(我们自己)all the morning."

关于东北三省的说法不正确的是（    ）