______, Edison didn’t have much schooling and he was taught by his mother.
A.When was a boy
B.A boy was when
C.Was a boy
D.When a boy

Mach numbers describe the velocity of airplanes ______ over the speed of sound.
A.have moved
B.move
C.moving
D.moved

Auroras are created when the sun’s particles are caught in ______.
A.field the earth’s magnetic
B.the field magnetic earth
C.the earth’s magnetic fields
D.the magnetic field earth

It is ______ that so many young people leave school without qualifications.
A.regretted
B.regrettable
C.regretful
D.to regret

Carpets from countries such as Persia and Afghanistan often fetch high prices in the United States.
A.Artifacts
B.Pottery
C.Rugs
D.Textiles

Though many scientific breakthroughs have resulted from mishaps it has taken brilliant thinkers to recognize their potential.
A.accidents
B.misunderstandings
C.incidentals
D.misfortunes

A.tattoo
B.taboo
C.igloo
D.shampoo

A.innovate
B.insolent
C.insistent
D.innocent

A.irrelevant
B.irreparable
C.irritable
D.irrational

A.subculture
B.vigorous
C.gadgetry
D.consensus