用所给单词适当形式填A:How many times()the doctor()(be）to America?B:He()(be)there three times.A:When()he()(go)there B:He()(go)there in1999,2001and2004.
问题描述：
用所给单词适当形式填A:How many times()the doctor()(be）to America?B:He()(be)there three times.
A:When()he()(go)there B:He()(go)there in1999,2001and2004.
答
1.has been has been the doctor第三人称，谓语用单数，而且是完成时，have been
2.did go went
过去式，根据后面的时间
答
How many times(has)the doctor(been)(be）to America?B:He(has been)(be)there three times.
When(did)he(go )(go)there B:He(went)(go)there in1999,2001and2004.