.... However, expenses have increased as well.为什么上面3句however前有的是用了; 但有的的仍然是, 为什么呢？2）I had arrived early as was my habit; I, therefore, felt priviledged to take my leave without delay.这句中therefore和I 前用了; 请教老师as was my habit中的as ...
The transition will be politically hard in places that have invested a lot in being covid-free.请问老师这里的being covid-free是动名词短语作in的宾语吧?我疑惑的是为什么要用being呢，不可以invested a lot in covid-free places吗？
...们在圣诞节时交换礼物。若交换的对象为不可数名词，则只能用单数。如：The
meetings provided an opportunity to exchange information. 这些会议提供了交流信息的机会。偶尔也接单数可数名词，但比较少见。如：Trevor and I exchanged a
glance. 特...
...e 2, showed a BSFC penalty of about 1.8% per 10 kPa back pressure increase when back pressure exceeded the back pressure limit for this engine.这里的per是不是就相当于 for every? 这句话证明per后面也可以跟不是“每一”的情况？谢谢老师！