题文
--When _____ the abacus _____? -- In the sixth century by the Chinese people.
| A．is, invented | B．did, invent |
| C．was, invented | D．does, invent |
--When _____ the abacus _____? -- In the sixth century by the Chinese people.
| A．is, invented | B．did, invent |
| C．was, invented | D．does, invent |
试题篮
()
粤公网安备 44130202000953号
