[单项选择]The experiments of two groups of rats indicate that _______.

[单项选择]The experiments of two groups of rats indicate that _______.

[单项选择]For two students ad D would be more economical than ad C because ______.
A. they would share a room
B. the basic expenses are cheaper
C. there are no extras except for food
D. there is free use of the garden

[单项选择]To which two great families or groups of families does the passage refer
A. the Yorkists and the Lancastrians
B. the Yorks and the Roses
C. the White and the Red
D. France and England

[单项选择]

Passage Three
All whales fall into two groups, those with teeth and those without. Both beluga and dolphin belong to the suborder of toothed whales known as Odontoceti, along with porpoises, narwhals, pilot whales, killer whales and the largest toothed creature in the world, the sperm whale. Size differences among the Odontoceti are remarkable. A common porpoise will run only 4 or 5 feet in length and 300 pounds in weight; a sperm whale may be 10 times as long and 300 times as heavy. The beluga falls in between, weighing up to 2,000 pounds. And it does chirp. In fact, it makes a great variety of squeaking, whistling, and clicking sounds, which have earned it the name of sea canary.
The toothless, or baleen, whales belong to the suborder of Mysticeti. This is a group of generally large whales, formerly abundant in all the oceans of the world. Though reduced by hunting, most species are still found along the coasts of the United Stated and Canada. All but two
A. The blue whale is larger than the sperm whale.
B. The beluga is larger than the blue whale.
C. The killer whale is larger than the sperm whale.
D. The porpoise is larger than the killer whale.

[单项选择]Telecommuting is less environmentally friendly than office-based work.

[单项选择]The rats fed unrestricted diets do NOT


A. have one preventing-aging protein increased.
B. have their cell death increased or doubled.
C. have their DNA fragmentation doubled.
D. have the levels of proteins increase