下列哪项不是胎怯病早产儿和足月儿两者间的鉴别要点（） A.胎龄 B.指甲 C.身长

正常胎儿整个大脑皮层脑裂形成时期为（）

A.12~16周 

B.17~23周 

C.24~26周 

D.27~29周 

E.30周以后 

The blue of the sea is caused by the scattering of sunlight by tiny particles suspended in the water. Blue light, being of short wavelength, is scattered more efficiently than light of longer wavelengths. Although waters of the open ocean are commonly some shade of blue, green water is commonly seen near coasts, especially in tropical or subtropical regions. This is caused by yellow pigments being mixed with blue water. Phytoplankton are one source of the yellow pigment. Other microscopic plants may color the water brown or brownish-red. Near the shore, silt or sediment in suspension can give water a brownish hue. Outflow of large rivers can often be observed many miles offshore by the coloration of suspended soil particles.Marine phytoplankton (Greek for "plant wanderers") are microscopic single-celled plants that include diatoms, dinoflagellates, coccolithophorids, green algae, and blue-green algae, among others. The growth of these organisms, which photosynthesize light, depends on a delicate balance of nutrient enrichment via vertical mixing, which is often limited by the availability of nitrogen and light. Diatoms are one-celled plants with patterned glass coverings. Each glass, or silicon dioxide box, is ornamented with species-specific designs, pits, and perforations making them popular with microscopists and, more recently, electron scanning microscopists.

The main idea of this passage is that________.

A．light causes sea color

B．sea coloration is varied because of a combination of length of light waves and microscopic plant life and silt

C．microscopic plant life causes sea color

D．water composition causes sea color

社会工作者李艳在社区进行家访时，有一位居民向她反映目前政府发放给他的低保金不能应付其家庭生活开支，加上自己身体不好，需经常吃药，生活十分拮据。这位居民还说最近天气很冷，而家中御寒棉被不够。李艳发现社区中还有不少居民与这位居民情况相似，她决定尝试为这些居民提供服务。在下述做法中，能够反映社区工作特点的有______。

A．向他们提供理财辅导和情绪疏导

B．自掏腰包替他们解决生活困难

C．动员志愿者，为低保户募集旧衣物和棉被等生活用品

D．召开低保户座谈会，听取他们的意见，商讨解决办法

E．向社区内所有低保户做问卷调查，了解他们的实际情况

野外测绘人员沿铁路、公路区域作业时，必须要做的是( )。

A．佩戴安全帽、安全灯
B．配备通信设备
C．穿着色彩醒目的带有安全警示反光的马夹
D．配备导航定位设备

违反治安管理的行为范畴包括( )。

A．扰乱公共秩序的行为
B．妨害公共安全的行为
C．侵犯人身权利、财产权利的行为
D．妨害社会管理的行为