托福考试

【单选题】Meteorites are slowed down by Earth’s atmosphere, but if they are moving （）, they can form a crater on impact. 
A. enough fast 
B. fast enough 
C. so fast enough 
D enough are fast 

【单选题】Most of North America receives （） some form of continuous plant cover except in the arid and semiarid Southwest. 
A. moisture to sustain sufficient 
B. sufficient moisture to sustain 
C. to sustain sufficient moisture 
D. sufficient to sustain moisture 

【单选题】 Which of the following can be in
A．( Many scientists could be expected to disagree with it
B．( evidence to support the theory has recently been found
C．( The theory is no longer seriously considered
D．( Most scientists believe the theory to be accurate

【单选题】 The author mentions the shoe industry in the second paragraph to provide an example of how
A．(entrepreneurs increased output by using an extended outwork system
B．(entrepreneurs used technological improvements to increase output
C．(rural workers responded to "shoe bosses"
D．(changes in the outwork system improved the quality of shoes

【单选题】 ________ is not clear to researchers.
A．Why dinosaurs having become extinct
B．Why dinosaurs became extinct
C．Did dinosaurs become extinct
D．Dinosaurs became extinct