It ______ long ago that the earth is round.
A: was discovered
B: is discovered
C: discovers
D: discovered
A: was discovered
B: is discovered
C: discovers
D: discovered
举一反三
- DNA is very useful for us, it many years ago. (1.0) A: discovers B: discovered C: is discovered D: was discovered
- He became very friendly when he ____________ that she was my sister. A: was discovered B: discovers C: has discovered D: discovered
- The scientist ________ a new bacteria in 1912. A: discovered B: was discovering C: discovers D: have discovered
- Copernicus (哥白尼) discovered an important (true) () when he learnt that the earth moves round the sun.
- The scientist ( )a new bacteria in 1912. A: discovered B: was discovering C: discovers