Dust and grime can dramatically reduce the efficiency of solar panels
灰尘和污垢会显著降低太阳能电池板的效率
Buildings were agreeably shrouded in grime .
建筑物愉快地笼罩在尘垢中。
It is not until a more advanced stage of urbanisation is reached-with 75 % of the population in cities ( like , say , northern egypt or rio de janeiro ) - that it makes any sense to spend a lot on such policies as slum clearances , lest the now-teeming city is split apart by crime and grime .
