磨削裂纹的磁痕一般垂直于磨削方向，呈平行线状或网状，有时还呈现出龟裂状。

Scientists are trying to make some small cars that may some day take the place of today’s big cars. If everyone drives such cars in the future, there will be 1_ pollution in the air. There will _2 be more space or parking cars in cities, and the _3_ will be less crowded. Three such cars can fit in__4__ that it is now needed for one car of the usual size.
The little cars will __5___ much less to own and to drive. Driving will be __6___, too, as these little cars can go only 65 kilometers per hour. The little cars of __7___ will be fine or getting out of the city, but they will not be useful for__8__ trips. Little cars which are powered by gasoline( 汽油 ) will go 450 kilometers __9___ needing to stop for more gasoline .
If big cars still are used together with the small ones, _10__ sets of roads will be needed in the future. Some roads will be used for the big, fast cars, and some roads will be needed for the slower, small ones.

小题1:	A．much B．less C．small D．more

小题2:	A．have B．also C．too D．less

小题3:	A．spaces B．streets C．shops D．building

小题4:	A．spaces B．the rooms C．the group D．the space

小题5:	A．spend B．take C．cost D．pay

小题6:	A．faster B．safer C．quick D．dangerous

小题7:	A．today B．todays C．the past D．the future

小题8:	A．short B．long C．any D．the shortest

小题9:	A．after B．then C．before D．while

小题10:

A．few B．two C．many D．little