Never should we forget the war and sufferings ________ caused to the people.

A．it

B．which

C．that

D．what

蚯蚓的刚毛有助于它在洞穴中运动，另外蚯蚓的钻穴等活动使土壤变得更加疏松和肥沃，这说明了

A．生物能适应环境

B．生物既能适应环境，又能影响环境

C．生物能影响环境

D．生物存在遗传现象