Professor Smith is also the _______ of the international program office. If you have any problem when you study here,you may go to him for help.
D
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Whenmakingmoderncameras,peoplebeganto_______plasticsformetal.
Healwayshasalotof_______ideasinhismind,andsometimeswedonotevenknowwhatheisthindingabout.
Manykindsofanimalsarebelievedtohave_________fromtheearth