可以用来换取粮票的食物只有这些：代用咖啡、通心粉和小块的人造黄油。There were few provisions available in exchange for food stamps: ersatz coffee, macaroni, small cubes of margarine.这一新的代用甜味剂是用一种野生植物制成的.The new substitute sweetener is made from a wild pl...
Many groups can be added by nucleophilic substitution on a diazonium salt.许多基团可通过向得自胶的重氮盐作亲核取代而加以导入.Most direct substitution of groups bound to an aromatic nucleus is limited to diazonium salts.大多数连于芳核能被直接取代的基团仅限于重氮盐....
玛丽亚正用儿语和小家伙说话。Maria was talking baby talk to the little one.“嗯，”他承认道，“我有时候说话的确有点吐字不清。”"Well," he conceded, "I do sometimes mumble a bit."在电视上说话时你必须很谨慎。You have to be careful what you say on telly....