在现代市场经济中，资本是承担风险和吸收损失的第一资金来源。( )

As viewed from space, the Earth’’s distinguishing characteristics are its blue waters and white clouds. Enveloped by an ocean of air consisting of 78% nitrogen and 21% oxygen, the planet is the only one in our solar system known to harbor life. Circling the Sun at an average distance of 149 million km (93 million miles), the Earth is the third planet from the Sun and the fifth largest planet in the solar system. Its rapid spin and molten nickel-iron core give rise to an extensive magnetic field which, coupled with the atmosphere, shields us from nearly all of the harmful radiation coming from the Sun and other stars. Most meteors burn up in the Earth’’s atmosphere before they can strike the surface. The planet’’s active geological processes have left no evidence of the ancient pelting it almost certainly received soon after it was formed. The Earth has a single natural satellite — the Moon.

Approximately how much of the Earth’s atmosphere is nitrogen

A．One-fourth.

B．One-half.

C．Three-fourths.

D．All of it.

《中华人民共和国食品卫生法》规定了对从事食品生产经营人员的要求，下列各项中不正确的说法是

A．食品生产经营人员应当保持个人卫生
B．食品生产经营人员应当经常进行健康检查
C．食品生产经营人员每年必须进行检查
D．食品生产经营人员在销售直接人口食品时，必须使用售货工具
E．食品生产经营人员生产、销售食品时，必须将手洗净，穿戴清洁工作衣、帽

洪水发生时，水利工程管理单位应采取的防备与自救措施有（）。

A.及时与当地或上级防汛、水文部门联系

B.掌握自己所在位置和周围环境，冷静选择最佳转移路线，做到心中有数

C.备足日常用品和救生设备等物资以备急需

D.保存好手机等通讯设备，以便应急联络

影响碎屑岩储集层孔隙率的因素有（）。

A、颗粒大小及分选程度

B、颗粒的排列方式及形状

C、胶结物

D、碎屑成分

倒档是通过在主从动两齿轮间加一个（）来实现的。

A、倒档驱动轮

B、倒档从动轮

C、倒档空转齿轮