熔断器在电路中可起到（）。
A、过载保护
B、短路保护
C、过载及短路保护
参考答案：B
____________ people went to the concert which was held in People’s Square the night of May Day.
A．Three thousand, in
B．Thousands, on
C．Many thousand, in
D．Thousands of, on
可见光的能量应为（）。
A.1.24×104～1.24×106eV
B.1.43×102～71eV2
C.6.2～3.1eV
D.3.1～1.65eV
