“They kept it a secret from me by dressing up as cleaning ladies”中“by”的作用是什么?

she always laughts at a good joke though it was late .they kept on working They kept trying _____ they must have known it was hopeless.A. if B. because C. when D. where It was a nuisance-----------( being kept/kept )waiting like that. tthough it was late,they kept on working “They kept it a secret from me by dressing up as cleaning ladies”中“by”的作用是什么? they have started an investigation,____are being kept secret,a/ the details of whichb/ the detail of it They kept to ask me a lot of questions改错! They urged that the library _________ open during the vacation.A.must be kept B.is kept C.would be kept D.be kept 22.They kept trying _____ they must have known it was hopeless.为什么用WHEN? kept on they had this really low doorway and I （kept on） hitting my head on it.这里填 kept on The doctor kept telling him that he mustn’t smoke,but ________ didn’t help.A.he B.which C.it D.they Where are the teachers?They're having a long meeting and it has ___four hoursA .kept B lasted C held D spent求原因 It was so cold that they kept the fire __ all night.A.to burnB.burnC.burningD.burned为什么?请详细说明每个选项. They kept on walking ＿＿they found a lake.填while还They kept on walking ＿＿they found a lake.填while还是when? It took a lickin' and kept on tickin They kept on working __________ it became completely dark.for since as if till They kept on working __________ it became completely dark.for since as if till they ___on walking until they found a lack.为什么用kept而不是continued