阅读下列材料，回答问题：

“太宗皇帝真长策，赚得英雄尽白头！”

北非民居的屋顶是平的，甚至是敞开的，这反映了当地的气候环境是(    )

阅读理解，判断正误。

Four Seasons

    Spring is the best season of the year. It lasts from March to May. The days get longer. The nights get shorter, and the weather gets warmer. Everything begins to grow. Grass and trees begin to turn green. Flowers begin to come out. Children begin to fly kites outdoors.

    Summer comes after spring.  It is the hottest season in the year. It lasts from June to August. People try to find a cool place then. They always go swimming in pools, lakes, and rivers.

    Autumn is the harvest season. It gets cool. Farmers begin to reap (收割).They are busy from September to November.

    The coldest season of the year is winter. It's from December to February. The days are short and the nights are long. It snows sometimes and that makes the children happy. They make a snowman and dance around it. They go ice-skating as well.

①将10.6g Na₂CO₃溶于100mL水中

②将28.6g Na₂CO₃•10H₂O溶于少量水中，再用水稀释至100mL

③将20ml 5.0mol/L Na₂CO₃溶液用水稀释至100mL．

若点P$\left(m,1\right)$在第二象限，则点B$\left(-m+1,-1\right)$必在第____ 象限。