大气压是由于空气受到重力而产生的．如果地球的表面约为5×10¹⁴m²，那么，在一个标准大气压下，地球周围的空气质量约为（标准大气压取1.0×10⁵Pa，g=10N/kg）（　　）

基因突变和染色体变异是真核生物可遗传变异的两种来源．回答下列问题：

有些食物中铁元素含量非常丰富，其中非血红素铁是其存在的形式之一，主要是三价铁与蛋白质和羧酸结合成络合物．

根据下列句子所给的汉语注释，写出单词的正确形式，使句子意思完整。每空只填一词。

1. Can you find Hepu on the ____ (地图) of Guangxi?

2.–-What does your aunt look like?

  ---She's of medium build, and she has long____ (头发).

3.---Which of the two T-shirts do you like better?

  ---The____ (黄色的) one.

4. My uncle goes fishing to relax every____ (星期天).

5. She began to learn to ____ (做饭) when she was eight years old.

6. When I'm down or tired, I ____ (更喜欢) movies that can cheer me up.

7. The geography teacher tells us that the Caspian Sea is 1,025 meters ____ (深的).

8. The boy who is often absent from classes will ____ (不及格) his exams this time.

9. Hangzhou is____ (广泛地) known for the West Lake and Longjing Tea.

10. There are over ____ (三十) new words in Unit 3 and I've already memorized all of them.