The researchers hypothesized that some of the ______ may help reduce a person's risk of colon concer.

A.A hypothetical example

B.A brief example

C.An extended example

D.none of the above

Biometeorologists are “researchers into human responses to academic lectures.” ()

Researchers hold that boredom results from______.

A．natural surroundings

B．various kinds of factors

C．sensitive personalities

D．subjective perceptions

A.ordered

B.held

C.accepted

D.tracked

A.precluded

B.excluded

C.concluded

D.included

A.treat

B.threaten

C.help

D.protect

Researchers have established the() between smoking and cancer.

A link

B chain

C join

D economy