Unlike the fossil fuels of today biofuels are renewable sources which mean that they wil

问题补充：

Unlike the fossil fuels of today, biofuels are renewable sources, which mean that they will not easily.

A. come out

B. break out

C. turn out

D. run out

答案：

A. come out

B. break out

C. turn out

(答案→)D. run out

解析：考查动词短语辨析。A出版发行；B（战争，火灾）爆发；C结果是，原来是，证明是；D用完，耗尽；句意：和现在的化石燃料不一样，生物燃料是可再生的资源，这意味着他们不会容易地就用完了。根据句意说明D项正确。