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The teacher is busy ____ correcting papers.

A. for                    B.in                   C.on             D.of

The teacher is busy ____ correcting papers.

A. for                    B.in                   C.on             D.of

The teacher is busy ____ correcting papers.

A. for                    B.in                   C.on             D.of

The teacher is busy ____ correcting papers.

A. for                    B.in                   C.on             D.of

The teacher is busy ____ correcting papers.

A. for                    B.in                   C.on             D.of