On weekdays, David gets up at 6:30.He has breakfast at seven and then he goes to school by bus. He gets there at 7:15. He doesn't like to be late. Classes begin at 8:00. He has lunch at twelve at school. He goes home at 5:30 in the afternoon. On weekends, he gets up at about 8:00 and makes breakfast for his family. His parents like him very much.

Look at the sky. I think it will be ____ (rain) soon.

著名进化论的建立者提出了人类和类人猿的共同祖先是一类古猿（　　）

引起生物可遗传的变异的原因有3种，即基因重组、基因突变和染色体变异。以下几种生物性状的产生，来源于同一种变异类型的是（      ）
①果蝇的白眼     ②豌豆的黄色皱粒、绿色圆粒     ③八倍体小黑麦的出现    ④人类的色盲     ⑤玉米的高茎皱叶    ⑥人类的镰刀型细胞贫血症