下列烃类中，为不饱和烃的是（）。A、烷烃； B、环烷烃； C、芳香烃； D、氯仿。

根据短文内容，将下面A—E五个句子分别填入文中空缺处，使补全后的短文意思通顺，结构完整。

Hip-hop dancing（街舞）is popular with many young people today.     小题1: They use this dance to show their love for life. It also shows that they feel good about life, that they just want to be themselves and enjoy life,     小题2:  

Hip-hop dancing has a history of more than 20 years.     小题3: In early times, it was seen in New York and Los Angles. At that time, many young black people often danced to the music in the streets. They used their legs, arms, heads and even shoulders to dance. Many young people still use most of these moves today.

Hip-hop dancing became popular all over the world because of the 1983 movie Flashdance. 

Some people performed Hip-hop dancing in the movie.     小题4:  They began to dance like them. Then it became popular.     小题5: new school and old school. More and more young people are learning Hip-hop dancing. People believe that it is a good way to exercise their bodies, and that it is good for their health.

患者男性，20岁，双眼视力进行性下降5年。角膜透明，曲率增加，角膜深层见基质板层垂直性条纹，前房加深，临床怀疑圆锥角膜。

圆锥角膜典型的三联症是（）。

A.Fleischer环、Vogt条纹、Arlt线

B.Vogt条纹、Arlt线、Munson征

C.Arlt线、Munson征、Herbt小凹

D.Fleischer环、Vogt条纹、Munson征

E.Fleischer环、Bitot斑、Munson征

会计教育不仅要传授必需的技巧与知识，而且要灌输道德标准和敬业精神。这是我国《会计法》的规定。 ( )

产褥期抑郁症症状最常见于（）

A.产后7天

B.产后72小时

C.产后24小时

D.产后2周

E.产后4周

工作分析系统的选择应慎重，主要应考虑哪些因素？