精子的头部含有什么（）。

[问答题]Practice 2　 Directions:　 Read the following text(s) and write an essay to　 1) summarize the main points of the text(s),　 2) make clear your own viewpoint, and　 3) justify your stand.　 In your essay, make full use of the information provided in the text(s). If you use more than three consecutive words from the text(s), use quotation marks (“ ”).　 You should write 160—200 words on the ANSWER SHEET.　 It is all very well to blame traffic congestion, the cost of petrol and the hectic pace of modern lift, but manners on the roads are becoming deplorable. Everybody knows that nicest men become monsters behind the wheel. It is all very well again to have a tiger in the tank, but to have one in the drivers seat is completely another awkward and difficult situation.　 You might tolerate the odd mad hog, but nowadays the well-mannered motorist is the exception to the rule. Perhaps the situation calls for a “Be Kind to Other Drivers” campaign; otherwise it may get completely out of hand.　 Road courtesy is not only good manners, but good sense too. It takes the most levelheaded and good-tempered of drivers to resist the temptation to retaliate when subjected to uncivilized behavior. On the other hand, a little courtesy goes a long way towards relieving the tensions and frustrations of motoring. A friendly nod or a wave of acknowledgement in response to an act of courtesy helps to create an atmosphere of goodwill and tolerance so necessary in modern traffic conditions. But such acknowledgements of courtesy are all too rare today. Many drivers nowadays don't even seem able to recognize courtesy when they see it.　 Lorry drivers say they have almost abandoned the practice of signaling cars to overtake when the road is clear, because many of the cars took too long to pass. Their drivers couldn't be bothered to select a lower gear. Others, after overtaking, slowed down again and hogged the road.　 They manufacture them by force, using their direction indicators as a threat rather than a warning. Slanting matches and even punch-ups（打架斗殴）are quite common. It can't be long before we hear of pistols and knives being used: we can then call our dual carriageways, and solve a spelling problem in the process. Driving is essentially a state of mind. However technically skilled a driver may be, he can't be all advanced motorist if he is always arrogant and aggressive.

[单选题]根据《化学品生产单位特殊作业安全规范》（GB 30871—2014)，化学品生产单位采用动火作业时,应有专人进行监火。下列关于动火作业要求的说法中，错误的是（）

[填空题]投注站参与“缩水、优化”为名的私彩活动的，一经发现将取消（），收回（），没收（）。

[单选题]汉武帝时，提出“罢黜百家，独尊儒术”的大儒是（）

[单选题]中西方社会文化之间存在着较大差异。在我国社会工作快速发展进程中，推动我国社会工作价值观与伦理规范本土化的正确态度应该是（　　）。

[单选题]突发性聋的听力急剧下降多发生在（）。

[单选题]正畸治疗过程中，以下哪种吸收与矫治力无关（）

[单选题]对施工现场进行绿色施工评价时，优选项措施到位，满足考评指标要求，则加（）分。

[问答题]种子检验意义或作用。

[单选题]扩张性货币政策主要指（　　）。

[单选题]精子的头部含有什么（）。

[填空题]精子头部的主要结构有（）和（）。

[填空题]叶绿素分子含有一个由（）组成的的“头部”和一个含有由（）组成的“尾巴”。

[填空题]犬的射精过程分阶段，真正含有大量精子的精液在第（）阶段。

[判断题]精子和卵子都是仅含有体细胞染色体数量的一半。

[填空题]精子的顶体覆盖在（）处，其内含有（）、（）和磷酸酯酶等多种水解酶。

[单选题]人类精子中含有的性染色体应为：（）

[填空题]X精子的DNA比Y精子（）。

[单选题]精子的顶体来自精子细胞的（）。

[名词解释题]精子活力/精子活率