ICs have been regarded as the most important invention in the Information Age for a long time.
举一反三
- Not until then did people know that John _________ important military information to the enemy for a long time.
- Not until then did people know that John _________ important military information to the enemy for a long time. A: had been selling B: sold C: would sell D: had sold
- Not until then did people know that he ________ important military information to the enemy for a long time. A: sold B: would sell C: had sold D: had been selling
- Manipulators that mimic human motions ________available for a long time. A: have B: been C: have been D: is
- These magazines___ in the library for a long time. A: have kept B: are keeping C: have been keeping D: have been kept