2023届高考英语语法填空练习第二期

高考语法填空练习第二期 A Adding bacteria can make concrete greener Concrete is one of the world’s most important materials. But making the cement that binds it generates about 8% of anthropogenic（人为的） carbon-dioxide emissions. This is not just 1._________ _______ the heat involved. That could, in principle, be supplied in 2.______________(environment) friendly ways. It is, rather,embedded in the very chemistry of the process. The heat is applied to limestone, to break up its principal constituent, calcium carbonate, into calcium oxide (cement’s crucial ingredient) and CO2. In a 3.___________(warm) world, this CO2 should be disposed of in a manner which keeps it 4._____ _____ the atmosphere. That is tricky. Better, then, not to generate it in the first place, by remodelling the way the aggregates that are concrete’s other ingredient are bound together. Intriguingly, this may be an area 5._________ microbes（细菌，微生物） can come to the rescue. Basilisk Healing Agent consists of tiny pellets（小球） that hold dried spores from a range of bacteria belonging to the genera Planococcus, Bacillus and Sporosarcina, together with nutrients including polylactic acid（聚乳酸）. Construction workers pour the pellets into conventional cement 6.________ mixing it with water and aggregate. The high alkalinity（碱度） of uncured cement stops the moisture activating the spores. That alkalinity drops, however, as the concrete cures. This means that, if a crack appears and water gets in, the spores in the 7. __________(embed) pellets are primed to spring into action and generate calcium carbonate. This fills in fissures（裂缝） up to a millimetre across, nipping potentially dangerous cracks in the bud. Not only does that lower maintenance costs, it also means the concrete concerned need contain less reinforcing steel, since the quantity of such “rebar” used in conventional concrete anticipates the extra strength which will 8.___________(need) as cracks inevitably form. A cubic metre of typical concrete thus requir