1、【题目】Insect pests are among the leading causes of crop failure.

选项：

A.expected

B.chief

C.natural

D.least

答案：

B

解析：

暂无解析

1、【题目】Food must be moist in order to have a taste.

选项：

A.appetizing(delicious)

B.nutritious

C.damp

D.chewed

答案：

C

解析：

暂无解析

1、【题目】Blue－greenalgaegrowabundantlyinsaltmarshes.

选项：

A.primarily

B.slowly

C.onplants(cultivate)

D.ingreatnumbers

答案：

解析：

1、【题目】TheNativeAmericaninterpreterSacajaweawasavaluablememberoftheLewisanddarkexpeditionin1805.

选项：

A.veryfriendly

B.veryuseful

C.verythoughtful.

D.verywealthy

答案：

解析：

1、【题目】TheSalkvaccineisamajorfactorinthefighttoeradicatepolio.

选项：

A.completelydestroy

B.carefullydisguise

C.sustain

D.contain

答案：

解析：