the common basilisk Basilicus basilicus，a lizard (蜥蜴) native to Central and South America．It can run across water for a distance of several meters，avoiding getting wet by rapidly hitting the water's surface with its feet．The lizard will take as many as 20 steps per second to keep moving forward．For humans to do this，we'd need huge feet that we could bring up to our ears in order to create adequate "hitting"．

But fortunately there is an alternative: cornflour．By adding enough of this common thickening agent to water(and it does take a lot)，you can create a "non-New'tonian" liquid that doesn't behave like normal water．Now，if the surface of the water is hit hard enough，particles (粒子) in the water group together for a moment to make the surface hard．Move quickly enough and put enough force into each step，and you really can walk across the surface of an adequately thick liquid of cornflour．

Fun though all this may sound，it's still rather messy and better read about in theory than carried out in practice．If you must do it，then keep the water wings handy in case you start to sink and take a shower afterward !

44．Walking on water hasn't become a reality mainly because humans ______ ．

A．are not interested in it

B．have biological limitations

C．have not invented proper tools

D．are afraid to make an attempt

45．What do we know about Basilicus basilicus from the passage?

A．It is light enough to walk on water．

B．Its huge feet enable it to stay above water．

C．It can run across water at a certain speed．

D．Its unique skin keeps it from getting wet in water．

46．What is the function of the cornflour according to the passage?

A．To create a thick liquid．

B．To turn the water into solid．

C．To help the liquid behave normally．

D．To enable the water to move rapidly．

47．What is the author's attitude toward the idea of humans' walking on water?

A．It is risky but beneficial．

B．It is interesting and worth trying．

C．It is crazy and cannot become a reality．

D．It is impractical though theoretically possible．

　　　　　　　　　　　　　　　 [三]

Should we allow modern buildings to be built next to older buildings in a historic area of a city? In order to answer this question，we must first examine whether people really want to preserve the historic feel of an area．Not all historical buildings are attractive．However，there may be other reasons - for example，economic(经济的) reasons - why they should be preserved．So，let us assume that historical buildings are both attractive and important to the majority of people．What should we do then if a new building is needed?

In my view，new architectural styles can exist perfectly well alongside an older