The ______ are running on the ______. A: deer …grasses B: deers …grass C: deer … grass D: deers … grasses

Many ___are eating ___. A: sheep;grass B: sheeps;grasses C: sheep;grasses D: sheeps;grass

Cellulosic ethanol is a _____ produced from wood, grasses, or the inedible parts of plants.

以下哪种宿根花卉不属于观赏草（Ornamental Grasses）

We can learn from the passage that the tired land has fully recovered ______. A: when grasses and other plants appear again B: when the treatment is given by nature alone C: after it has been lying idle for ten years D: after grasses and other plants have decayed again

A group of __________ are eating ________ and_________ at the foot of the hill. A: sheep, grass, leaves B: sheeps, grasses, leaves C: sheep, grass, leaf D: sheeps, grass, leaf

According to the passage, what was the first great step toward the practice of agriculture A: The invention of agricultural implements and machinery. B: The development of a system of names for plants. C: The discovery of grasses that could be harvested and replanted. D: The changing diets of early humans.

Which of the following is part of a positive feedback mechanism associated with global climate change? A: increase in the gas mileage of cars B: increase in the cloudiness caused by more moisture in the atmosphere C: melting of Arctic sea ice D: increase in the acidity of seawater E: increase in the growth of CO2 absorbing trees and grasses