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The Bunsen Burner is so named because it is thought ___________ by Robert Bunsen.

A. to be invented                   B. having been invented

C. invented                         D. to have been invented

The Bunsen Burner is so named because it is thought ___________ by Robert Bunsen.

A. to be invented               B. having been invented

C. invented                     D. to have been invented

The Bunsen Burner is so named because it is thought ___________ by Robert Bunsen.

A. to be invented               B. having been invented

C. invented                     D. to have been invented

The Bunsen Burner is so named because it is thought ___________ by Robert Bunsen.

  A. to be invented               B. having been invented

  C. invented                     D. to have been invented

The Bunsen Burner is so named because it is thought ___________ by Robert Bunsen.

A. to be invented　　　　　　　 B. having been invented

C. invented　　　　　　　　　 D. to have been invented