They have many different ways to create electricity. But some ways are ________

题干

They have many different ways to create electricity. But some ways are ________ to the environment and easily cause air pollution.

A．helpful

B．helpless

C．harmful

D．harmless

上一题下一题 0.65难度单选题更新时间:2019-03-27 09:03:27

小学学科试题库

初中学科试题库

高中学科试题库