A.is | B.has been | C.are | D.have been |
A.has done | B.has been done | C.have done | D.have been done |
A.is | B.are | C.was | D.were |
A.has argued | B.has been arguing |
C.have argued | D.have been arguing (争论,辩论,争吵,劝说) |
A.have been | B.are | C.has been | D.has |
A.attends | B.attend | C.are attending | D.have attended |
A.grazes | B.is grazing | C.was grazing | D.were grazing |
A.is | B.are | C.were | D.be |
A.knows | B.know | C.is known | D.are known |
A.become | B.has become | C.becomes | D.is becoming |