问题

Which of the following sentences doesn’tcontain(包含) an object clause(宾语从句)

A:Many peoplebelieve robots will do most of our work
B:Scientistsshould be able to develop plants that grow on Mars
C:People thinkthat humans on Mars have to wear special boots to make themselves heavier
D:We all knowthe next Olympic Games will be held in Beijing
正确答案是: