Africancities are forecast to urbanize（城市化）at a rate of3.65% annually, adding nearly 350 million newcity-dwellers by 2030, according to The Brookings Institution. A billion morepeople are expected to be living in African cities by 2063.

Populationgrowth is the engine of urbanization for the continent. Most of the expansionin urban populations comes from natural growth not rural-to urban migration.Already, big cities like Lagos and Kinshasa are growing rapidly—and with thatgrowth comes many challengers.

Mostof Africa’s worst problems are most obvious in its cities, the huge numbers ofpeople, the unemployed everywhere, the endless traffic jams, the bad roadnetworks, the absence of meaningful infras -tructure（基礎(chǔ)設(shè)施）---it goes on.

Yet,（66）thereare three recurring difficulties with Africa’s rapid urbanization, according toa World Bank report out this mouth.

First,the cities are crowded. That might seem obvious to a visitor. Both commercialand industrial and housing infrastructure investment has been unable to keep upwith the rise in urban population.

Thenthere’s the poor transport network of these cities. Residents are unable toeasily move from one part of the city to another due to unreliable andinefficient transport networks made up of minibuses, matatus which travel across these cities.

Finally,it’s expensive to live, invest, of run a business in an African city. (67)TheWord Bank says African cities are 29%more expensive than cities in countries atsimilar income levels. Families in African cities in countries an similarincome levels. Families in African cities have to spend 55%more on housing thanother regions. The high transport, housing, and food costs make labor moreexpensive.

(68) Asmany people hit middle age, they often start to notice that their memory andmental clarity are not what they used to be. We suddenly can’t rememberwhere we put the keys just a moment ago or an old acquaintance’s name, or thename of an old band we used to an old acquaintance’s name, or the name of anold band we used to love. As the brain fades, we sometimes refer to theseoccurrences as“seniormoments”,whileseemingly innocent, this loss of mental focus can potentially have a harmfulimpact on our professional, social, and personal well-being.

Ithappens to most of us, but is it inevitable? Neuroscientists（神經(jīng)學(xué)家）are increasingly showing that there’s actually a lot that can bedone. It turns that the brain needs exercise in much the same way our musclesdo .and the right mental workouts can significantly improve our basic cognitive（認(rèn)知）functions. Thinking is essentially a process of making neuralconnections that drive intelligence is inherited. However, because theseconnections are made through effort and practice, scientists believe thatintelligence can expand and is unstable according to mental effort.

Now, anew San Francisco Web-based company has taken it a step further and developedthe first “brain training program” designed to actually help people improve andregain their mental sharpness. Called Lumosity, it was designed by some of theleading experts in neuroscience and cognitive psychology from StanfordUniversity.

Lumosityis far more than on online place to exercise your mental skills. That’s becausethey have integrated these exercises into a web-based program that allows youto systematically improve your memory and attention skills. The program keepstrack of your progress and provides detailed feedback on your performance andimprovement. Most importantly, it constantly modifies and enhances the gamesyou play to build on the strengths you are developing---much as an effectiveexercise routine requires you to increase resistance and vary your muscle use.

   A question that often troubles foodcompanies is how to control problems like rats and insects without harming thefood. Pest control experts say poisons should never be used where they mayenter food. They say the first line of defense against pests is to clean theplaces where food is handled or stored.

Floors, foodpreparation surfaces and tools can be disinfected with chemicals like  chlorine（氯）,iodine （碘）orbromine（溴）.Foodcontainers should be stored about half a meter off the ground and about a halfmeter away from any walls. Storage areas should be kept dry and clean.

Containersfor raw materials such as rice , wheat, etc. should be kept closed andclean.(69)Any foodstuff spilt during delivery or handling should be clearedup both inside and outside the building. Pests enter a building fromoutside , so pay attention to outer walls. Small stones can be used to coverthe ground and block the growth of plants and areas of grass should be keptshort to deny pests a place to live.

Check thatdoors and windows are completely closed. Also any hole that might allow pests toenter a building should be filled. Rats enter through a hole the size of acoin. A mouse can pass through a hole half that size.

Supervisorsshould make a list of pest control measures to be taken by employees. This willaid the efforts and also help prepare for any inspections. In most countries, thereis a food and drug administration bureau, or some agency with a similar name,which enforces rules nationwide, responsible for rules about the use ofpesticides, etc.

(70)However,businesses where food is stored, prepared of sold must also follow state andlocal health laws. Mostof these governmental departments or bureaus and other issues. People caneasily access the information.

One daya police officer managed to get some fresh mushrooms. He was so ____ what hehad bought that he offered to ____the mushrooms with his brother officers.

“Let thedog ____a piece first,” suggested one ___officer who was afraid that themushrooms might be poisonous. The dog seemed to ____his mushrooms, and theofficers then began to eat their meal saying that the mushrooms had a verystrange but quite pleasant taste.

An hourlater, however, they were all astonished when the gardener rushed in and said____the dog was dead. ____,the officers jumped into their cars and rushed intothe nearest hospital. Pumps（泵）were used and the officers had a very ____time getting rid of themushrooms that ___in their stomachs. Later, the gardener was called to  tell the way ____the poor dog had died. Thegardener answered,” It was killed the moment a car hit it.”

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