On returning home,I found I ___umbrella in the office.
A.had left B.have left C.left D.would leave
正确答案是A,为什么不选B或者C
Once you ____a promise,you must carry it out.
A.have made B.had made C.made D.is making
正确答案是A为什么不选C
3.The singer lived in California until he ___ to university.
A.had sent B.was sending C.had been sent D.was sent
选D,为什么不选C