一个袋子中有4个球，其中2个红球，2个蓝球，除颜色外其余特征均相同，若从这个袋子中任取1个球，是蓝色的概率是（   ）

继科学家发现C₃O₂是金星大气的成分后，2004年，美国科学家通过“勇气”号太空探测出火星大气中含有一种称为硫化碳（化学式为COS）的物质。已知硫化碳与二氧化碳的结构相似，但在氧气中会燃烧。下列说法中不正确的是

用所给动词的正确时态、语态填空
⑴Be quiet, please ! The baby____ (sleep).
⑵—What does Frank often do at weekends?
—He often____ (go) to the cinema with his parents.
⑶Andy ____ (argue) with his brother when I went to see him yesterday.
⑷She ____ (be) to her hometown several times.
⑸____ (play) computer games too much is bad for your eyes.
⑹Lucy tried ____(not make) too many mistakes in the exam.
⑺He ____  to us as soon as he gets there. (write)
⑻By the time I got outside, the bus____ (leave).
⑼I'm sure I ____  her four years ago. (see)
⑽In summer,  Miss Xia would rather ____  (stay) at home than go out.

下列句子中，划线字的字形和注音都完全正确的一项是（    ）

下图是某生物基因结构，有关说法正确的是（    ）