21.Inability to build high-voltage generators and motors gives to the transformer immediate recognition as a highly flexible link between the generation and distribution of electrical energy.
制造高压发电机和高压电动机是不可能的,这就立即使人们认识到变压器是发电与配电之 间灵活性很高的中间环节。 (本句是简单句。主语是inability,谓语是gives,宾语是recognition。不定式短语to build。..motors作定语,修饰inability。give recognition to...as..·,“承认……是……”。介词短语between—.energy作定语,修饰link。)
22.The mildness of its climate,with slight temperature variations and infrequent rainfall,combined with a high average level of sunshine and brilliant shies,a11 make it idea for tourism whether by winter or by summer.
宜人的气候、变化不大的温度、稀少的雨量、灿烂的阳光以及明媚的天空,所有这一切使 突尼斯成为冬夏理想的旅游胜地。(with...和combined with把三个主语连接起来。all是总括词,总括上述的三个主语。idea是it宾语补足语。it代替上文中Tunisia突尼斯。bywinter...这里by作“当……时候”解。例:They don’t work by day but by night.他们日间不工作,夜间工作。whether..or,“不论是……还是”,用作连词,连接两个并列成分。)
23.We explain the differences between gases and liquids bysaying that the molecules in a liquid are not moving about so fredy as the molecules in a gas and are very much closer together.