单项选择题

Since 1939, numerous scientific studies ______.

A．proved smoking causes fatal diseases
B．proved smoking causes life-shorting diseases
C．proved smoking is a health risk
D．had been made to prove whether smoking causes life shorting

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单项选择题

Cigar and pipe smokers consume ______.

A．slightly less nicotine than cigarette smokers
B．less nicotine than cigarette smokers
C．no less nicotine than cigarette smokers
D．much less nicotine than cigarette smokers

单项选择题

Amputation of limbs (Par

A．6 ) means ______.A. cutting off legs or armsB. disease of legs or armsC. curing of legs or armsD. discomfort of legs or arms