如图为氯化钠和硝酸钾的溶解度曲线，请回答：

（1）硝酸钾、氯化钠都属于____物质（填“易溶”、“可溶”、“微溶”或“难溶”）。
（2）当硝酸钾溶液从20℃升高30℃时，溶液中溶质质量分数将____（选填“变大”或“变小”或“不变”）。
（3）20℃时向100g水中加入25g硝酸钾，所得溶液为____溶液（填“饱和”或“不饱和”）；将上述溶液恒温蒸发掉50g水后，析出的固体质量是____g。

    One night last February, seventeen-year-old Duffy drove home1 a winding road, he saw a 2light thrown against the tree. “I knew it wasn't the moon”, he said. “I drive this road 3and I notice little things 4”

    Duffy stopped his car and got out to 5Below him far down in the deep valley 6a broken car with its headlights on. Thirty minutes 7a man had driven off the edge of the road, which has no guardrail（护栏）. His car fell and8over, landing on its top more than two hundred feet 9

    Duffy 10to call for help, then returned and got down to reach the 11driver. Snow covered the valley and the temperature was below 12After struggling back up the cliff（悬岸）, Duffy 13his jacket and shirt and wrapped the injured man in time, along with the blankets from his 14.

   15deeds are starting to become16action for Duffy, the oldest of seven children. When he was 12, he17his ten-year-old brother from drowning（溺水）. Two years ago, his three-year-old sister 18rat poison（毒药）, and Duffy cleaned out her mouth, made her drink milk to protect her 19and called doctors.

    “We have tried to teach the children good 20and it looks like we have got some reward for it,” his father says.

已知集合$M=\left\{x|\left|x-7\right|<9\right\}$，$N=\left\{x|y=\sqrt{9-x^2}\right\}$，且$M,N$都是全集$U$的子集，则右图中阴影部分表示的集合是        （   ）