they are doing better there work 请问用哪个介词,

they are doing better there work 请问用哪个介词, They work we are doing is（ they are doing better in English now是DO BETTER IN 的现在进行时,请问大 If there is someone doing better than we are.为什么用doing They are doing their homework carefully.you'd better not---- Computer are wonderful m________.They can work better and fa the volunteers are doing difficult and important work,they s ______important work she is doing!hard they are ______workin These days they are busy ( ) the farm work填介词 They are staying there ()three weeks 括号内填介词 这句话对么?they would work better if they are in a good mood. what are they doing now?they work in a bank 对么