Unlike some mammals—cows and sheep, for instance—that are notably _____, lions have a wide range of facial expressions.

A：tractable

B：impassive

C：solitary

D：social

E：sluggish

答案：B

The research on otters’ environmental requirements is surprisingly (i)_____. One reason for this has to do with the estimation of how much they use different areas. Doing so may be (ii)_____ in some kinds of terrain, such as Shetland where the Eurasian otters are active in daytime and have clear individual markings. There it is possible to identify the individuals over stretches of coast of a few kilometers and to see what kinds of coast they use. However, the field conditions are (iii)_____.

Blank (I)Blank (II)Blank (III)

A：straightforward D：quite problematic G：routine

B：controversial E：relatively simple H：deceptive

C：difficult F：largely unnecessary I：exceptional

答案：CEI

Early practitioners of the natural sciences developed methods to remove distortions caused by either the research environment or the researcher. Such methods, especially with respect to the researcher, were considered to (i)_____ those (ii)_____ subjectivity whose unbridled expression was thought to (iii)_____ research.

Blank (I)Blank (II)Blank (III)

A：restrain D：incursions of G：corrupt

B：reveal E：restrictions on H：justification

C：disguise F：acknowledgements of I：expedite

答案：ADG

Although one can adduce myriad of examples of ecosystem disruption by nonindigenous species, nevertheless most introduced species that survive in fact appear to have quite _____ effects on the ecosystem they have invaded.

A：minimal

B：trifling

C：marked

D：conspicuous

E：intriguing

F：deleterious

答案：AB

At Cerro Portezuelo, the task of separating grinding tools from the larger collection of excavated stone objects was (i)_____ the ancient practice of recycling grinding tool fragments for building materials, hammer stones, and other purposes that (ii)_____ their original use.

Blank (I)Blank (II)

A：complicated by D：complemented

B：important to E：obscured

C：independent from F：underscored

答案：AE