什么是光伏效应?
参考答案:
指光照使不均匀半导体或半导体与金属结合的不同部位之间产生电位差的现象。
Usually there might be a lot of accidents in the heavy fog. I happened to witness ______ this morning. [ ]
A. it
B. those
C. one
D. that
除某些特殊情况下,黑洞与外界的热平衡是()平衡。