Scientists think that there _____ life on Earth for millions of years.
A: has had
B: have had
C: has been
D: have been
A: has had
B: have had
C: has been
D: have been
举一反三
- In the last few years,there________great changes in the country. A: had been B: were C: have been D: has been
- Every means______tried but with no end. A: have been B: have had C: has been D: are
- He Beijing four times. A: has been to B: had been to C: had gone to D: have been to
- The patient______ in the hospital for a week. A: has been B: is C: have been D: had been
- This is one of the best novels that ______ appeared this year. A: have been B: has C: had been D: have