【题目】It _____ Mike and Mary who helped the old man several days ago.
A. was B. are C. were D. had been
【题目】目前,海洋能源开发不广泛的原因是( )
A. 蕴藏能量比较有限,开发价值不大
B. 有污染,大规模开发会带来比较多的环境污染问题
C. 能量密度比较小,需要比较大的投入
D. 能量分布在远海,难以开发
【题目】It _____ Mike and Mary who helped the old man several days ago.
A. was B. are C. were D. had been
【题目】目前,海洋能源开发不广泛的原因是( )
A. 蕴藏能量比较有限,开发价值不大
B. 有污染,大规模开发会带来比较多的环境污染问题
C. 能量密度比较小,需要比较大的投入
D. 能量分布在远海,难以开发