Atachometer blank the blank at which an engine runs.

A tachometer measures the speed at which engine runs.

Explanation:

A tachometer or revolution-counter is measuring the rotation speed and it is an instrument. The speed is shown on the display.

dr. kings dream speech

explanation:

it was late in the day and hot, and after a long march and an afternoon of speeches about federal legislation, unemployment and racial and social justice, the rev. dr. martin luther king jr. finally stepped to the lectern, in front of the lincoln memorial, to address the crowd of 250,000 gathered on the national mall.