为什么加TO BE They are playful,sociable and just incredibly fun TO BE around

为什么加TO BE They are playful,sociable and just incredibly fun TO BE around they are sure to be Who are they talking to?to什么时候加?为什么加?Where do you live?为什么不加in?什么时候加? 这段英语前面为什么要加bethe drinks here are expensive.really?they used to be cheap.请有经验的来谈谈请通俗一点 They will be invited to my birthday party.Invited 后面为什么要加to呢? to be honest 为什么加to be They are books.book为什么加s mobile phones are not so expensive as they ------------- to be为什么这里填used they are so much better(to look at) than concrete.为什么不是be looked at under no circumstances (are they to borrow )our car tomorrow?请问为什么是这个答案,为什么不能用别的A:they are borrowing ,B: are they to borrow ,C: they will borrow ,D:could they be borrowing.求 They are talking each other 哪里有错误?为什么加about 那为什么不加to 呢 under no circumstance （） our car tomorrow?a are they to borrow b could they be borrowing选哪个为什么? Here are so many lovely flowers , They must be put into six sees 为什么see要加s?must 后为什么要加be They usually watch TV after supper.But this time they are listening to the radio.为什么watch不加es they just show that they are trying to be friendly提问that they are trying to be friendly We are less credulous than we used to be.这句话里面used后面为什么要加to be people who cannot distinguish between colours are said to be colour-blind.said后面为什么加to be they are not opened中为什么加个are?